Compounds Useful as RET Inhibitors

ABSTRACT

The present invention relates to compounds of formula I that function as inhibitors of RET (rearranged during transfection) kinase enzyme activity: 
     
       
         
         
             
             
         
       
     
     wherein HET, bonds a, b, c and d, X 1 , X 2 , X 3 , X 4 , R 2 , and R 3  are each as defined herein. The present invention also relates to processes for the preparation of these compounds, to pharmaceutical compositions comprising them, and to their use in the treatment of proliferative disorders, such as cancer, as well as other diseases or conditions in which RET kinase activity is implicated.

INTRODUCTION

The present invention relates to certain compounds that function as inhibitors of RET (rearranged during transfection) kinase enzyme activity. The present invention also relates to processes for the preparation of these compounds, to pharmaceutical compositions comprising them, and to their use in the treatment of proliferative disorders, such as cancer, as well as other diseases or conditions in which RET kinase activity is implicated.

BACKGROUND OF THE INVENTION

Cancer is caused by uncontrolled and unregulated cellular proliferation. Precisely what causes a cell to become malignant and proliferate in an uncontrolled and unregulated manner has been the focus of intense research over recent decades. This research has led to the identification of a number of molecular targets associated with key metabolic pathways that are known to be associated with malignancy.

RET (REarranged during Transfection) is a receptor tyrosine kinase (RTK) that forms part of a macromolecular receptor complex containing dimerized RET receptor, two co-receptors and a bound ligand. The glial derived neurtrophic factor (GDNF) family of ligands bind RET in association with one of four glycosyl phosphatidylinositol (GPI) anchored GDNF family α-receptors (GFRα). Ligand binding to the corresponding GFRα co-receptor triggers RET dimerization followed by trans-phosphorylation of intracellular signalling cascades. These downstream signalling networks play a key role in regulating cell survival, differentiation, proliferation, migration and chemotaxis.

Activating mutations in RET have been identified in familial and sporadic forms of medullary thyroid carcinomas (MTC) (Santoro & Carlomagno 2006; Schulmberger et al. 2008; Wells & Santoro 2009) and these correlate with aggressive disease progression (Elisei et al. 2008). Clinical benefit has been observed in MTC patients using the small molecule VEGFR2/EGFR inhibitor vandetanib (Wells et al. 2011) which has recently been approved by the FDA & EMEA. RET inhibition is a secondary pharmacology of this agent, which also targets VEGFR2 (Vascular endothelial growth factor receptor, also known as KDR—kinase insert domain receptor) and EGFR (epidermal growth factor receptor). The clinical benefit in MTC is considered to be due to RET inhibition but is unfortunately accompanied by significant side effects (rash, hypertension, diarrhoea) due to inhibition of EGFR and/or VEGFR. Furthermore, vandetanib also exhibits off-target activity versus hERG. Collectively all of these unwanted pharmacological activities may compromise its use in advanced MTC and also its extrapolation into earlier clinical settings (e.g. adjuvant).

Furthermore, several recent publications (Ju et al., 2012; Lipson et al., 2012; Kohno et al., 2012; Wang et al., 2012; Chao et al., 2012) describe various RET fusion translocations (e.g. KIF5B-RET and CCDC6-RET) present in approximately 1% of NSCLC (non-small cell lung carcinoma) patient samples, which may offer an important alternative disease segment in which a specific RET inhibitor would offer clinical benefit.

Therefore, there is a requirement for the development of more selective inhibitors of RET, in particular inhibitors that show less inhibition of KDR. It is anticipated that these more selective inhibitors will produce the desired therapeutic benefits associated with RET inhibition without the side effects associated with significant KDR inhibition. Such inhibitors will offer the potential of better therapy for cancers such as MTC and NSCLC and will widen the scope for the clinical use of RET inhibitors in earlier disease settings.

It is therefore an object of the present invention to provide further inhibitors of RET kinase enzyme activity.

Another object of the present invention is to provide inhibitors of RET kinase enzyme activity that show a greater selectivity for the inhibition of RET kinase relative to the inhibition of KDR.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein.

According to a further aspect of the present invention, there is provided a pharmaceutical composition comprising a compound as defined herein, or a pharmaceutically acceptable salt, hydrate or solvate thereof, in admixture with a pharmaceutically acceptable diluent or carrier.

According to a further aspect of the present invention, there is provided a method of inhibiting RET kinase enzyme activity in vitro or in vivo, said method comprising contacting a cell with an effective amount of a compound or a pharmaceutically acceptable salt, hydrate or solvate thereof as defined herein.

According to a further aspect of the present invention, there is provided a method of selectively inhibiting RET kinase enzyme activity over KDR enzyme activity in vitro or in vivo, said method comprising contacting a cell with an effective amount of a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein.

According to a further aspect of the present invention, there is provided a method of inhibiting cell proliferation, in vitro or in vivo, said method comprising contacting a cell with an effective amount of a compound or a pharmaceutically acceptable salt, hydrate or solvate thereof as defined herein, or a pharmaceutical composition as defined herein.

According to a further aspect of the present invention, there is provided a method of treating a disease or disorder in which RET kinase activity is implicated in a patient in need of such treatment, said method comprising administering to said patient a therapeutically effective amount of a compound or a pharmaceutically acceptable salt, hydrate or solvate thereof as defined herein, or a pharmaceutical composition as defined herein.

According to a further aspect of the present invention, there is provided a method of treating a proliferative disorder in a patient in need of such treatment, said method comprising administering to said patient a therapeutically effective amount of a compound or a pharmaceutically acceptable salt, hydrate or solvate thereof as defined herein, or a pharmaceutical composition as defined herein.

According to a further aspect of the present invention, there is provided a method of treating cancer in a patient in need of such treatment, said method comprising administering to said patient a therapeutically effective amount of a compound or a pharmaceutically acceptable salt, hydrate or solvate thereof as defined herein, or a pharmaceutical composition as defined herein.

According to a further aspect of the present invention, there is provided a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, or a pharmaceutical composition as defined herein for use in therapy.

According to a further aspect of the present invention, there is provided a compound or a pharmaceutically acceptable salt, hydrate or solvate thereof as defined herein, or a pharmaceutical composition as defined herein, for use in the treatment of a proliferative condition.

According to a further aspect of the present invention, there is provided a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, or a pharmaceutical composition as defined herein for use in the treatment of cancer. In a particular embodiment, the cancer is human cancer.

According to a further aspect of the present invention, there is provided a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein for use in the inhibition of RET kinase enzyme activity.

According to a further aspect of the present invention, there is provided a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein for use in the selective inhibition of RET kinase enzyme activity relative to KDR enzyme activity.

According to a further aspect of the present invention, there is provided a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein for use in the treatment of a disease or disorder in which RET kinase activity is implicated.

According to a further aspect of the present invention, there is provided the use of a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein in the manufacture of a medicament for the treatment of a proliferative condition.

Suitably, the proliferative disorder is cancer, suitably a human cancer (for Example medullary thyroid cancer (MTC)).

According to a further aspect of the present invention, there is provide the use of a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein in the manufacture of a medicament for the treatment of cancer.

According to a further aspect of the present invention, there is provided a use of a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein in the manufacture of a medicament for the inhibition of RET kinase enzyme activity.

According to a further aspect of the present invention, there is provided a use of a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein in the manufacture of a medicament for the selective inhibition of RET kinase enzyme activity relative to KDR enzyme activity.

According to a further aspect of the present invention, there is provided a use of a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein in the manufacture of a medicament for the treatment of a disease or disorder in which RET kinase activity is implicated.

According to a further aspect of the present invention, there is provided a process for preparing a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein.

According to a further aspect of the present invention, there is provided a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, obtainable by, or obtained by, or directly obtained by a process of preparing a compound as defined herein.

According to a further aspect of the present invention, there are provided novel intermediates as defined herein which are suitable for use in any one of the synthetic methods set out herein.

Features, including optional, suitable, and preferred features in relation to one aspect of the invention may also be features, including optional, suitable and preferred features in relation to any other aspect of the invention.

DETAILED DESCRIPTION OF THE INVENTION Definitions

Unless otherwise stated, the following terms used in the specification and claims have the following meanings set out below.

It is to be appreciated that references to “treating” or “treatment” include prophylaxis as well as the alleviation of established symptoms of a condition. “Treating” or “treatment” of a state, disorder or condition therefore includes: (1) preventing or delaying the appearance of clinical symptoms of the state, disorder or condition developing in a human that may be afflicted with or predisposed to the state, disorder or condition but does not yet experience or display clinical or subclinical symptoms of the state, disorder or condition, (2) inhibiting the state, disorder or condition, i.e., arresting, reducing or delaying the development of the disease or a relapse thereof (in case of maintenance treatment) or at least one clinical or subclinical symptom thereof, or (3) relieving or attenuating the disease, i.e., causing regression of the state, disorder or condition or at least one of its clinical or subclinical symptoms.

A “therapeutically effective amount” means the amount of a compound that, when administered to a mammal for treating a disease, is sufficient to effect such treatment for the disease. The “therapeutically effective amount” will vary depending on the compound, the disease and its severity and the age, weight, etc., of the mammal to be treated.

In this specification the term “alkyl” includes both straight and branched chain alkyl groups. References to individual alkyl groups such as “propyl” are specific for the straight chain version only and references to individual branched chain alkyl groups such as “isopropyl” are specific for the branched chain version only. For Example, “(1-6C)alkyl” includes (1-4C)alkyl, (1-3C)alkyl, propyl, isopropyl and t-butyl. A similar convention applies to other radicals, for Example “phenyl(1-6C)alkyl” includes phenyl(1-4C)alkyl, benzyl, 1-phenylethyl and 2-phenylethyl.

The term “(m-nC)” or “(m-nC) group” used alone or as a prefix, refers to any group having m to n carbon atoms.

An “alkylene,” “alkenylene,” or “alkynylene” group is an alkyl, alkenyl, or alkynyl group that is positioned between and serves to connect two other chemical groups. Thus, “(1-6C)alkylene” means a linear saturated divalent hydrocarbon radical of one to six carbon atoms or a branched saturated divalent hydrocarbon radical of three to six carbon atoms, for Example, methylene, ethylene, propylene, 2-methylpropylene, pentylene, and the like.

“(2-6C)alkenylene” means a linear divalent hydrocarbon radical of two to six carbon atoms or a branched divalent hydrocarbon radical of three to six carbon atoms, containing at least one double bond, for Example, as in ethenylene, 2,4-pentadienylene, and the like.

“(2-6C)alkynylene” means a linear divalent hydrocarbon radical of two to six carbon atoms or a branched divalent hydrocarbon radical of three to six carbon atoms, containing at least one triple bond, for Example, as in ethynylene, propynylene, and butynylene and the like.

“(3-8C)cycloalkyl” means a hydrocarbon ring containing from 3 to 8 carbon atoms, for Example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl or bicyclo[2.2.1]heptyl.

“(3-8C)cycloalkenyl” means a hydrocarbon ring containing at least one double bond, for Example, cyclobutenyl, cyclopentenyl, cyclohexenyl or cycloheptenyl, such as 3-cyclohexen-1-yl, or cyclooctenyl.

“(3-8C)cycloalkyl-(1-6C)alkylene” means a (3-8C)cycloalkyl group covalently attached to a (1-6C)alkylene group, both of which are defined herein.

The term “halo” or “halogeno” refers to fluoro, chloro, bromo and iodo.

The term “heterocyclyl”, “heterocyclic” or “heterocycle” means a non-aromatic saturated or partially saturated monocyclic, fused, bridged, or spiro bicyclic heterocyclic ring system(s). Monocyclic heterocyclic rings contain from about 3 to 12 (suitably from 3 to 7) ring atoms, with from 1 to 5 (suitably 1, 2 or 3) heteroatoms selected from nitrogen, oxygen or sulfur in the ring. Bicyclic heterocycles contain from 7 to 17 member atoms, suitably 7 to 12 member atoms, in the ring. Bicyclic heterocyclic(s) rings may be fused, spiro, or bridged ring systems. Examples of heterocyclic groups include cyclic ethers such as oxiranyl, oxetanyl, tetrahydrofuranyl, dioxanyl, and substituted cyclic ethers. Heterocycles containing nitrogen include, for Example, azetidinyl, pyrrolidinyl, piperidinyl, piperazinyl, tetrahydrotriazinyl, tetrahydropyrazolyl, and the like. Typical sulfur containing heterocycles include tetrahydrothienyl, dihydro-1,3-dithiol, tetrahydro-2H-thiopyran, and hexahydrothiepine. Other heterocycles include dihydro-oxathiolyl, tetrahydro-oxazolyl, tetrahydro-oxadiazolyl, tetrahydrodioxazolyl, tetrahydro-oxathiazolyl, hexahydrotriazinyl, tetrahydro-oxazinyl, morpholinyl, thiomorpholinyl, tetrahydropyrimidinyl, dioxolinyl, octahydrobenzofuranyl, octahydrobenzimidazolyl, and octahydrobenzothiazolyl. For heterocycles containing sulfur, the oxidized sulfur heterocycles containing SO or SO₂ groups are also included. Examples include the sulfoxide and sulfone forms of tetrahydrothienyl and thiomorpholinyl such as tetrahydrothiene 1,1-dioxide and thiomorpholinyl 1,1-dioxide. A suitable value for a heterocyclyl group which bears 1 or 2 oxo (═O) or thioxo (═S) substituents is, for Example, 2-oxopyrrolidinyl, 2-thioxopyrrolidinyl, 2-oxoimidazolidinyl, 2-thioxoimidazolidinyl, 2-oxopiperidinyl, 2,5-dioxopyrrolidinyl, 2,5-dioxoimidazolidinyl or 2,6-dioxopiperidinyl. Particular heterocyclyl groups are saturated monocyclic 3 to 7 membered heterocyclyls containing 1, 2 or 3 heteroatoms selected from nitrogen, oxygen or sulfur, for Example azetidinyl, tetrahydrofuranyl, tetrahydropyranyl, pyrrolidinyl, morpholinyl, tetrahydrothienyl, tetrahydrothienyl 1,1-dioxide, thiomorpholinyl, thiomorpholinyl 1,1-dioxide, piperidinyl, homopiperidinyl, piperazinyl or homopiperazinyl. As the skilled person would appreciate, any heterocycle may be linked to another group via any suitable atom, such as via a carbon or nitrogen atom. However, reference herein to piperidino or morpholino refers to a piperidin-1-yl or morpholin-4-yl ring that is linked via the ring nitrogen.

By “bridged ring systems” is meant ring systems in which two rings share more than two atoms, see for Example Advanced Organic Chemistry, by Jerry March, 4^(th) Edition, Wiley Interscience, pages 131-133, 1992. Examples of bridged heterocyclyl ring systems include, aza-bicyclo[2.2.1]heptane, 2-oxa-5-azabicyclo[2.2.1]heptane, aza-bicyclo[2.2.2]octane, aza-bicyclo[3.2.1]octane and quinuclidine.

By “spiro bi-cyclic ring systems” we mean that the two ring systems share one common spiro carbon atom, i.e. the heterocyclic ring is linked to a further carbocyclic or heterocyclic ring through a single common spiro carbon atom. Examples of spiro ring systems include 6-azaspiro[3.4]octane, 2-oxa-6-azaspiro[3.4]octane, 2-azaspiro[3.3]heptanes, 2-oxa-6-azaspiro[3.3]heptanes, 7-oxa-2-azaspiro[3.5]nonane, 6-oxa-2-azaspiro[3.4]octane, 2-oxa-7-azaspiro[3.5]nonane and 2-oxa-6-azaspiro[3.5]nonane.

“Heterocyclyl(1-6C)alkyl” means a heterocyclyl group covalently attached to a (1-6C)alkylene group, both of which are defined herein.

The term “heteroaryl” or “heteroaromatic” means an aromatic mono-, bi-, or polycyclic ring incorporating one or more (for Example 1-4, particularly 1, 2 or 3) heteroatoms selected from nitrogen, oxygen or sulfur. The term heteroaryl includes both monovalent species and divalent species. Examples of heteroaryl groups are monocyclic and bicyclic groups containing from five to twelve ring members, and more usually from five to ten ring members.

The heteroaryl group can be, for Example, a 5- or 6-membered monocyclic ring or a 9- or 10-membered bicyclic ring, for Example a bicyclic structure formed from fused five and six membered rings or two fused six membered rings. Each ring may contain up to about four heteroatoms typically selected from nitrogen, sulfur and oxygen. Typically the heteroaryl ring will contain up to 3 heteroatoms, more usually up to 2, for Example a single heteroatom. In one embodiment, the heteroaryl ring contains at least one ring nitrogen atom. The nitrogen atoms in the heteroaryl rings can be basic, as in the case of an imidazole or pyridine, or essentially non-basic as in the case of an indole or pyrrole nitrogen. In general the number of basic nitrogen atoms present in the heteroaryl group, including any amino group substituents of the ring, will be less than five.

Examples of heteroaryl include furyl, pyrrolyl, thienyl, oxazolyl, isoxazolyl, imidazolyl, pyrazolyl, thiazolyl, isothiazolyl, oxadiazolyl, thiadiazolyl, triazolyl, tetrazolyl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, 1,3,5-triazenyl, benzofuranyl, indolyl, isoindolyl, benzothienyl, benzoxazolyl, benzimidazolyl, benzothiazolyl, benzothiazolyl, indazolyl, purinyl, benzofurazanyl, quinolyl, isoquinolyl, quinazolinyl, quinoxalinyl, cinnolinyl, pteridinyl, naphthyridinyl, carbazolyl, phenazinyl, benzisoquinolinyl, pyridopyrazinyl, thieno[2,3-b]furanyl, 2H-furo[3,2-b]-pyranyl, 5H-pyrido[2,3-d]-o-oxazinyl, 1H-pyrazolo[4,3-d]-oxazolyl, 4H-imidazo[4,5-d]thiazolyl, pyrazino[2,3-d]pyridazinyl, imidazo[2,1-b]thiazolyl, imidazo[1,2-b][1,2,4]triazinyl. “Heteroaryl” also covers partially aromatic bi- or polycyclic ring systems wherein at least one ring is an aromatic ring and one or more of the other ring(s) is a non-aromatic, saturated or partially saturated ring, provided at least one ring contains one or more heteroatoms selected from nitrogen, oxygen or sulfur. Examples of partially aromatic heteroaryl groups include for Example, tetrahydroisoquinolinyl, tetrahydroquinolinyl, 2-oxo-1,2,3,4-tetrahydroquinolinyl, dihydrobenzthienyl, dihydrobenzfuranyl, 2,3-dihydro-benzo[1,4]dioxinyl, benzo[1,3]dioxolyl, 2,2-dioxo-1,3-dihydro-2-benzothienyl, 4,5,6,7-tetrahydrobenzofuranyl, indolinyl, 1,2,3,4-tetrahydro-1,8-naphthyridinyl, 1,2,3,4-tetrahydropyrido[2,3-b]pyrazinyl and 3,4-dihydro-2H-pyrido[3,2-b][1,4]oxazinyl.

Examples of five membered heteroaryl groups include but are not limited to pyrrolyl, furanyl, thienyl, imidazolyl, furazanyl, oxazolyl, oxadiazolyl, oxatriazolyl, isoxazolyl, thiazolyl, isothiazolyl, pyrazolyl, triazolyl and tetrazolyl groups.

Examples of six membered heteroaryl groups include but are not limited to pyridyl, pyrazinyl, pyridazinyl, pyrimidinyl and triazinyl.

A bicyclic heteroaryl group may be, for Example, a group selected from:

a benzene ring fused to a 5- or 6-membered ring containing 1, 2 or 3 ring heteroatoms; a pyridine ring fused to a 5- or 6-membered ring containing 1, 2 or 3 ring heteroatoms; a pyrimidine ring fused to a 5- or 6-membered ring containing 1 or 2 ring heteroatoms; a pyrrole ring fused to a 5- or 6-membered ring containing 1, 2 or 3 ring heteroatoms; a pyrazole ring fused to a 5- or 6-membered ring containing 1 or 2 ring heteroatoms; a pyrazine ring fused to a 5- or 6-membered ring containing 1 or 2 ring heteroatoms; an imidazole ring fused to a 5- or 6-membered ring containing 1 or 2 ring heteroatoms; an oxazole ring fused to a 5- or 6-membered ring containing 1 or 2 ring heteroatoms; an isoxazole ring fused to a 5- or 6-membered ring containing 1 or 2 ring heteroatoms; a thiazole ring fused to a 5- or 6-membered ring containing 1 or 2 ring heteroatoms; an isothiazole ring fused to a 5- or 6-membered ring containing 1 or 2 ring heteroatoms; a thiophene ring fused to a 5- or 6-membered ring containing 1, 2 or 3 ring heteroatoms; a furan ring fused to a 5- or 6-membered ring containing 1, 2 or 3 ring heteroatoms; a cyclohexyl ring fused to a 5- or 6-membered heteroaromatic ring containing 1, 2 or 3 ring heteroatoms; and a cyclopentyl ring fused to a 5- or 6-membered heteroaromatic ring containing 1, 2 or 3 ring heteroatoms.

Particular Examples of bicyclic heteroaryl groups containing a six membered ring fused to a five membered ring include but are not limited to benzfuranyl, benzthiophenyl, benzimidazolyl, benzoxazolyl, benzisoxazolyl, benzthiazolyl, benzisothiazolyl, isobenzofuranyl, indolyl, isoindolyl, indolizinyl, indolinyl, isoindolinyl, purinyl (e.g., adeninyl, guaninyl), indazolyl, benzodioxolyl and pyrazolopyridinyl groups.

Particular Examples of bicyclic heteroaryl groups containing two fused six membered rings include but are not limited to quinolinyl, isoquinolinyl, chromanyl, thiochromanyl, chromenyl, isochromenyl, chromanyl, isochromanyl, benzodioxanyl, quinolizinyl, benzoxazinyl, benzodiazinyl, pyridopyridinyl, quinoxalinyl, quinazolinyl, cinnolinyl, phthalazinyl, naphthyridinyl and pteridinyl groups.

“Heteroaryl(1-6C)alkyl” means a heteroaryl group covalently attached to a (1-6C)alkylene group, both of which are defined herein. Examples of heteroaralkyl groups include pyridin-3-ylmethyl, 3-(benzofuran-2-yl)propyl, and the like.

The term “aryl” means a cyclic or polycyclic aromatic ring having from 5 to 12 carbon atoms. The term aryl includes both monovalent species and divalent species. Examples of aryl groups include, but are not limited to, phenyl, biphenyl, naphthyl and the like. In particular embodiment, an aryl is phenyl.

The term “aryl(1-6C)alkyl” means an aryl group covalently attached to a (1-6C)alkylene group, both of which are defined herein. Examples of aryl-(1-6C)alkyl groups include benzyl, phenylethyl, and the like.

This specification also makes use of several composite terms to describe groups comprising more than one functionality. Such terms will be understood by a person skilled in the art. For Example heterocyclyl(m-nC)alkyl comprises (m-nC)alkyl substituted by heterocyclyl.

The term “optionally substituted” refers to either groups, structures, or molecules that are substituted and those that are not substituted. The term “wherein a/any CH, CH₂, CH₃ group or heteroatom (i.e. NH) within a R¹ group is optionally substituted” suitably means that (any) one of the hydrogen radicals of the R¹ group is substituted by a relevant stipulated group.

Where optional substituents are chosen from “one or more” groups it is to be understood that this definition includes all substituents being chosen from one of the specified groups or the substituents being chosen from two or more of the specified groups.

The phrase “compound of the invention” means those compounds which are disclosed herein, both generically and specifically.

Compounds of the Invention

In one aspect, the present invention relates to compounds, or pharmaceutically acceptable salts, hydrates or solvates thereof, having the structural formula (I) shown below:

wherein:

-   -   HET is selected from one of the following:

-   -   wherein         denotes the point of attachment;     -   R₁ is selected from hydrogen, (1-4C)haloalkyl, (1-4C)haloalkoxy         or a group of the formula:

-L-Y-Q

-   -   wherein:         -   L is absent or (1-5C)alkylene optionally substituted by one             or more substituents selected from (1-2C)alkyl or oxo;         -   Y is absent or O, S, SO, SO₂, N(R_(a)), C(O), C(O)O, OC(O),             C(O)N(R_(a)), N(R_(a))C(O), N(R_(a))C(O)N(R_(b)),             N(R_(a))C(O)O, OC(O)N(R_(a)), S(O)₂N(R_(a)), or N(R_(a))SO₂,             wherein R_(a) and R_(b) are each independently selected from             hydrogen or (1-4C)alkyl; and         -   Q is hydrogen, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl,             aryl, (3-10C)cycloalkyl, (3-10C)cycloalkenyl, heteroaryl or             heterocyclyl; wherein Q is optionally further substituted by             one or more substituent groups independently selected from             (1-4C)alkyl, halo, (1-4C)haloalkyl, (1-4C)haloalkoxy, amino,             (1-4C)aminoalkyl, cyano, hydroxy, carboxy, carbamoyl,             sulphamoyl, mercapto, ureido, NR_(c)R_(d), OR_(c),             C(O)R_(c), C(O)OR_(c), OC(O)R_(c), C(O)N(R_(d))R_(c),             N(R_(d))C(O)R_(c), S(O)_(y)R_(c) (where y is 0, 1 or 2),             SO₂N(R_(d))R_(c), N(R_(d))SO₂R_(c), Si(R_(d))(R_(c))R_(e) or             (CH₂)_(z)NR_(d)R_(c) (where z is 1, 2 or 3); wherein R_(c),             R_(d) and R_(e) are each independently selected from             hydrogen, (1-6C)alkyl or (3-6C)cycloalkyl; or R_(c) and             R_(d) can be linked such that, together with the nitrogen             atom to which they are attached, they form a 4-7 membered             heterocyclic ring which is optionally substituted by one or             more substituents selected from (1-4C)alkyl, halo,             (1-4C)haloalkyl, (1-4C)haloalkoxy, (1-4C)alkoxy,             (1-4C)alkylamino, amino, cyano or hydroxy; or         -   Q is optionally substituted by a group of the formula:

-L₁-L_(Q1)-Z₁

-   -   -   wherein:             -   L₁ is absent or (1-3C)alkylene optionally substituted by                 one or more substituents selected from (1-2C)alkyl or                 oxo;             -   L_(Q1) is absent or selected from or O, S, SO, SO₂,                 N(R_(f)), C(O), C(O)O, OC(O), C(O)N(R_(f)),                 N(R_(f))C(O), N(R_(g))C(O)N(R_(f)), N(R_(f))C(O)O,                 OC(O)N(R_(f)), S(O)₂N(R_(f)), or N(R_(f))SO₂, wherein                 R_(f) and R_(g) are each independently selected from                 hydrogen or (1-2C)alkyl; and             -   Z₁ is hydrogen, (1-6C)alkyl, aryl, aryl(1-2C)alkyl,                 (3-8C)cycloalkyl, (3-8C)cycloalkenyl, heteroaryl or                 heterocyclyl; wherein Z₁ is optionally substituted by                 one or more substituents selected from (1-4C)alkyl,                 halo, (1-4C)haloalkyl, (1-4C)haloalkoxy, (1-4C)alkoxy,                 (1-4C)alkylamino, amino, cyano, hydroxy, carboxy,                 carbamoyl, sulphamoyl, mercapto, ureido, aryl,                 heteroaryl, heterocycyl, (3-6C)cycloalkyl, NR_(h)R_(i),                 OR_(h), C(O)R_(h), C(O)OR_(h), OC(O)R_(h),                 C(O)N(R_(i))R_(h), N(R_(i))C(O)R_(h), S(O)_(y)R_(h)                 (where y is 0, 1 or 2), SO₂N(R_(i))R_(b),                 N(R_(i))SO₂R_(h) or (CH₂)_(z)NR_(l)R_(h) (where z is 1,                 2 or 3); wherein R_(h) and R_(i) are each independently                 selected from hydrogen, (1-4C)alkyl or (3-6C)cycloalkyl;

    -   R_(1a) and R_(1b) are each selected from H, (1-4C)alkyl, halo,         (1-4C)haloalkyl, (1-4C)haloalkoxy, (1-4C)alkoxy,         (1-4C)alkylamino, amino, cyano, hydroxy, carboxy, carbamoyl,         sulphamoyl or mercapto;

    -   W is selected from O, S or NR¹, wherein R¹ is selected from H or         (1-2C)alkyl; bonds a, b, c and d are independently selected from         a single or double bond;

    -   X₁ and X₂ are each independently selected from N or CR_(j) when         bond a is a double bond, or NR_(k) or CR_(j)R_(k) when bond a is         a single bond;

    -   wherein         -   R_(j) is selected from hydrogen, halo, (1-4C)alkyl,             (1-4C)alkoxy, amino, (1-4C)alkylamino, (1-4C)dialkylamino,             cyano, (2C)alkynyl, C(O)R_(j1), C(O)OR_(j1), OC(O)R_(j1),             C(O)N(R_(j2))R₁, N(R_(j2))C(O)R_(j1), S(O)_(y)R_(j1) (where             y is 0, 1 or 2), SO₂N(R_(j2))R_(j1), N(R_(j2))SO₂R₁ or             (CH₂)_(z)NR_(j1)R_(j2) (where z is 1, 2 or 3); wherein said             (1-4C)alkyl is optionally substituted by one or more             substituents selected from amino, hydroxy, (1-2C)alkoxy or             halo;         -   R_(k) and R_(j) are independently selected from hydrogen or             (1-4C)alkyl;         -   and         -   R_(j1) and R_(j2) are each independently selected from             hydrogen or (1-4C)alkyl;

    -   X₃ is selected from N or CR_(l) when bond b is a double bond, or         NR_(m) or CR_(l)R_(m) when bond b is a single bond;

    -   wherein         -   R_(l) is selected from hydrogen, halo, (1-4C)alkyl,             (1-4C)alkoxy, amino, (1-4C)alkylamino, (1-4C)dialkylamino,             cyano, (2C)alkynyl, C(O)R_(l1), C(O)OR_(l1), OC(O)R_(l1),             C(O)N(R_(l2))R_(l1), N(R_(l2))C(O)R_(l1), S(O)_(y)R_(l1)             (where y is 0, 1 or 2), SO₂N(R_(l2))R_(l1),             N(R_(l2))SO₂R_(l1) or (CH₂)_(z)NR_(l2)R_(l1) (where z is 1,             2 or 3); wherein said (1-4C)alkyl is optionally substituted             by one or more substituents selected from amino, hydroxy,             (1-2C)alkoxy or halo;         -   R_(l) and R_(m) are independently selected from hydrogen or             (1-4C)alkyl;         -   and         -   R_(l1) and R_(l2) are each independently selected from             hydrogen or (1-4C)alkyl;

    -   X₄ is selected from N or CR_(n) when bond d is a double bond, or         NR_(o) or CR_(n)R_(o) when bond d is a single bond;

    -   wherein         -   R_(n) is selected from hydrogen, halo, (1-4C)alkyl,             (1-4C)alkoxy, amino, (1-4C)alkylamino, (1-4C)dialkylamino,             cyano, (2C)alkynyl, C(O)R_(n1), C(O)OR_(n1), OC(O)R_(n1),             C(O)N(R_(n2))R_(n1), N(R_(n2))C(O)R_(n1), S(O)_(y)R_(n1)             (where y is 0, 1 or 2), SO₂N(R_(n2))R_(n1),             N(R_(n2))SO₂R_(n1) or (CH₂)_(z)NR_(n1)R_(n2) (where z is 1,             2 or 3); wherein said (1-4C)alkyl is optionally substituted             by one or more substituents selected from amino, hydroxy,             (1-2C)alkoxy or halo;         -   R_(n) and R_(o) are independently selected from hydrogen or             (1-4C)alkyl;         -   and         -   R_(n1) and R_(n2) are each independently selected from             hydrogen or (1-4C)alkyl;

    -   R₂ is selected from hydrogen, (1-4C)alkyl or a group of the         formula:

-L₂-Y₂-Q₂

-   -   wherein:         -   L₂ is absent or (1-3C)alkylene optionally substituted by one             or more substituents selected from (1-2C)alkyl or oxo;         -   Y₂ is absent or C(O), C(O)O, C(O)N(R_(p)), wherein R_(p) is             selected from hydrogen or (1-4C)alkyl; and         -   Q₂ is hydrogen, (1-6C)alkyl, aryl, (3-8C)cycloalkyl,             (3-8C)cycloalkenyl, heteroaryl or heterocyclyl; wherein Q₂             is optionally further substituted by one or more substituent             groups independently selected from (1-4C)alkyl, halo,             (1-4C)haloalkyl, (1-4C)haloalkoxy, amino, cyano, hydroxy,             carboxy, carbamoyl, sulphamoyl, NR_(q)R_(r), OR_(q), wherein             R_(q) and R_(r) are each independently selected from             hydrogen, (1-4C)alkyl or (3-6C)cycloalkyl;     -   R₃ is selected from a group of the formula:

—Y₃-Q₃

-   -   wherein:         -   Y₃ is C(O), C(O)N(R_(s)), N(R_(s))(O)C, C(O)OR_(s),             OC(O)CR_(s), triazole, oxadiazole or tetrazole, wherein             R_(s) is selected from hydrogen or (1-2C)alkyl; and         -   Q₃ is hydrogen, (1-6C)alkyl, (1-6C)alkoxy, aryl,             aryl(1-2C)alkyl, (3-8C)cycloalkyl, (3-8C)cycloalkenyl,             heteroaryl or heterocyclyl; wherein Q₃ is optionally further             substituted by one or more substituent groups independently             selected from (1-4C)alkyl, halo, (1-4C)haloalkyl,             (1-4C)haloalkoxy, amino, cyano, hydroxy, carboxy, carbamoyl,             sulphamoyl, NR_(t)R_(u), OR_(t), wherein R_(t) and R_(a) are             each independently selected from hydrogen, (1-4C)alkyl or             (3-6C)cycloalkyl; or Q₃ is optionally substituted by a group             of the formula:

-L₄-L_(Q4)-Z₄

-   -   -   wherein:             -   L₄ is absent or (1-3C)alkylene optionally substituted by                 one or more substituents selected from (1-2C)alkyl or                 oxo;             -   L_(Q4) is absent or selected from or O, S, SO, SO₂,                 N(R_(v)), C(O), C(O)O, OC(O), C(O)N(R_(v)),                 N(R_(v))C(O), N(R_(w))C(O)N(R_(v)), N(R_(v))C(O)O,                 OC(O)N(R_(v)), S(O)₂N(R_(v)), or N(R_(v))SO₂, wherein                 R_(v) and R_(w) are each independently selected from                 hydrogen or (1-2C)alkyl; and             -   Z₄ is hydrogen, (1-6C)alkyl, aryl, aryl(1-2C)alkyl,                 (3-8C)cycloalkyl, (3-8C)cycloalkenyl, heteroaryl or                 heterocyclyl; wherein Z₄ is optionally substituted by                 one or more substituents selected from (1-4C)alkyl,                 halo, (1-4C)haloalkyl, (1-4C)haloalkoxy, (1-4C)alkoxy,                 (1-4C)alkylamino, amino, cyano, hydroxy, carboxy,                 carbamoyl, sulphamoyl, mercapto, ureido, aryl,                 heteroaryl, heterocycyl, (3-6C)cycloalkyl, NR_(x)R_(y),                 OR_(x), C(O)R_(x), C(O)OR_(x), OC(O)R_(x),                 C(O)N(R_(y))R_(x), N(R_(y))C(O)R_(x), S(O)_(y)R_(x)                 (where y is 0, 1 or 2), SO₂N(R_(y))R_(x),                 N(R_(y))SO₂R_(x) or (CH₂)_(z)NR_(x)R_(y) (where z is 1,                 2 or 3); wherein R_(x) and R_(y) are each independently                 selected from hydrogen, (1-4C)alkyl or (3-6C)cycloalkyl;

with the proviso that only one or two of X₁, X₂, X₃ or X₄ can be N.

Particular compounds of the invention include, for Example, compounds of the formula I, or pharmaceutically acceptable salts, hydrates and/or solvates thereof, wherein, unless otherwise stated, each of HET, R₁, R_(1a), R_(1b), W, bonds a, b, c and d, X₁, X₂, X₃, X₄, R₂ and R₃ and any associated substituent groups has any of the meanings defined hereinbefore or in any of paragraphs (1) to (44) hereinafter:—

-   (1) HET is selected from one of the following:

-   (2) HET is selected from one of the following:

-   (3) HET is:

-   (4) R₁ is selected from hydrogen, (1-4C)haloalkyl, (1-4C)haloalkoxy     or a group of the formula:

-L-Y-Q

-   -   wherein:         -   L is absent or (1-5C)alkylene optionally substituted by one             or more substituents selected from (1-2C)alkyl or oxo;         -   Y is absent or O, S, SO, SO₂, N(R_(a)), C(O), C(O)O, OC(O),             C(O)N(R_(a)), N(R_(a))C(O), S(O)₂N(R_(a)), or N(R_(a))SO₂,             wherein R_(a) and R_(b) are each independently selected from             hydrogen or (1-4C)alkyl; and         -   Q is hydrogen, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl,             aryl, (3-10C)cycloalkyl, (3-10C)cycloalkenyl, heteroaryl or             heterocyclyl;     -   wherein Q is optionally further substituted by one or more         substituent groups independently selected from (1-4C)alkyl,         halo, (1-4C)haloalkyl, (1-4C)haloalkoxy, amino,         (1-4C)aminoalkyl, cyano, hydroxy, carboxy, carbamoyl,         sulphamoyl, mercapto, ureido, NR_(c)R_(d), OR_(c), C(O)R_(c),         C(O)OR_(c), OC(O)R_(c), C(O)N(R_(d))R_(c), N(R_(d))C(O)R_(c),         S(O)_(y)R_(c) (where y is 0, 1 or 2), SO₂N(R_(d))R_(c),         N(R_(d))SO₂R_(c), Si(R_(d))(R_(c))R_(e) or (CH₂)_(z)NR_(d)R_(c)         (where z is 1, 2 or 3); wherein R_(c), R_(d) and R_(e) are each         independently selected from hydrogen, (1-6C)alkyl or         (3-6C)cycloalkyl; or R_(c) and R_(d) can be linked such that,         together with the nitrogen atom to which they are attached, they         form a 4-7 membered heterocyclic ring which is optionally         substituted by one or more substituents selected from         (1-4C)alkyl, halo, (1-4C)haloalkyl, (1-4C)haloalkoxy,         (1-4C)alkoxy, (1-4C)alkylamino, amino, cyano or hydroxy; or         -   Q is optionally substituted by a group of the formula:

-L₁-L_(Q1)-Z₁

-   -   -   wherein:             -   L₁ is absent or (1-3C)alkylene optionally substituted by                 one or more substituents selected from (1-2C)alkyl;             -   L_(Q1) is absent or selected from or O, S, SO, SO₂,                 N(R_(f)), C(O), C(O)O, OC(O), C(O)N(R_(f)),                 N(R_(f))C(O), N(R_(f))C(O)O, S(O)₂N(R_(f)), or                 N(R_(f))SO₂, wherein R_(f) and R_(g) are each                 independently selected from hydrogen or (1-2C)alkyl; and             -   Z₁ is hydrogen, (1-6C)alkyl, aryl, aryl(1-2C)alkyl,                 (3-8C)cycloalkyl, (3-8C)cycloalkenyl, heteroaryl or                 heterocyclyl;

    -   wherein Z₁ is optionally substituted by one or more substituents         selected from (1-4C)alkyl, halo, (1-4C)haloalkyl,         (1-4C)haloalkoxy, (1-4C)alkoxy, (1-4C)alkylamino, amino, cyano,         hydroxy, carboxy, carbamoyl, sulphamoyl, mercapto, ureido, aryl,         heteroaryl, heterocycyl, (3-6C)cycloalkyl, NR_(h)R_(i) or         OR_(h), wherein R_(h) and R_(i) are each independently selected         from hydrogen, 1-4C)alkyl or (3-6C)cycloalkyl;

-   (5) R₁ is selected from hydrogen, (1-4C)haloalkyl, (1-4C)haloalkoxy     or a group of the formula:

-L-Y-Q

-   -   wherein:         -   L is absent or (1-3C)alkylene optionally substituted by one             or more substituents selected from (1-2C)alkyl or oxo;         -   Y is absent or O, N(R_(a)), C(O), C(O)O, OC(O),             C(O)N(R_(a)), N(R_(a))C(O), S(O)₂N(R_(a)), or N(R_(a))SO₂,             wherein R_(a) and R_(b) are each independently selected from             hydrogen or (1-4C)alkyl; and         -   Q is hydrogen, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl,             aryl, (3-10C)cycloalkyl, (3-10C)cycloalkenyl, heteroaryl or             heterocyclyl;     -   wherein Q is optionally further substituted by one or more         substituent groups independently selected from (1-4C)alkyl,         halo, (1-4C)haloalkyl, (1-4C)haloalkoxy, amino,         (1-4C)aminoalkyl, cyano, hydroxy, carboxy, carbamoyl,         sulphamoyl, mercapto, ureido, NR_(c)R_(d), OR_(c), C(O)R_(c),         C(O)OR_(c), OC(O)R_(c), C(O)N(R_(d))R_(c), N(R_(d))C(O)R_(c),         S(O)_(y)R_(c) (where y is 0, 1 or 2), SO₂N(R_(d))R_(c),         N(R_(d))SO₂R_(c), Si(R_(d))(R_(c))R_(e) or (CH₂)_(z)NR_(d)R_(c)         (where z is 1, 2 or 3); wherein R_(c), R_(d) and R_(e) are each         independently selected from hydrogen, (1-6C)alkyl or         (3-6C)cycloalkyl; or R_(c) and R_(d) can be linked such that,         together with the nitrogen atom to which they are attached, they         form a 4-7 membered heterocyclic ring which is optionally         substituted by one or more substituents selected from         (1-4C)alkyl, halo, (1-4C)haloalkyl, (1-4C)haloalkoxy,         (1-4C)alkoxy, (1-4C)alkylamino, amino, cyano or hydroxy; or         -   Q is optionally substituted by a group of the formula:

-L₁-L_(Q1)-Z₁

-   -   -   wherein:             -   L₁ is absent or (1-3C)alkylene optionally substituted by                 one or more substituents selected from (1-2C)alkyl;             -   L_(Q1) is absent or selected from or N(R_(f)), C(O),                 C(O)O, OC(O), C(O)N(R_(f)), N(R_(f))C(O) or                 N(R_(f))C(O)O, wherein R_(f) and R_(g) are each                 independently selected from hydrogen or (1-2C)alkyl; and             -   Z₁ is hydrogen, (1-6C)alkyl, aryl, aryl(1-2C)alkyl,                 (3-8C)cycloalkyl, (3-8C)cycloalkenyl, heteroaryl or                 heterocyclyl; wherein Z₁ is optionally substituted by                 one or more substituents selected from (1-4C)alkyl,                 halo, (1-4C)haloalkyl, (1-4C)haloalkoxy, (1-4C)alkoxy,                 (1-4C)alkylamino, amino, cyano, hydroxy,                 (3-6C)cycloalkyl, NR_(h)R_(i) or OR_(h), wherein R_(h)                 and R_(i) are each independently selected from hydrogen,                 (1-4C)alkyl or cycloalkyl;

-   (6) R₁ is selected from hydrogen, (1-4C)haloalkyl, (1-4C)haloalkoxy     or a group of the formula:

-L-Y-Q

-   -   wherein:         -   L is absent or (1-3C)alkylene optionally substituted by one             or more substituents selected from (1-2C)alkyl or oxo;         -   Y is absent or O, N(R_(a)), C(O), C(O)O, OC(O),             C(O)N(R_(a)), N(R_(a))C(O), S(O)₂N(R_(a)), or N(R_(a))SO₂,             wherein R_(a) and R_(b) are each independently selected from             hydrogen or (1-4C)alkyl; and         -   Q is hydrogen, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl,             aryl, (3-10C)cycloalkyl, (3-10C)cycloalkenyl, heteroaryl or             heterocyclyl; wherein Q is optionally further substituted by             one or more substituent groups independently selected from             (1-4C)alkyl, halo, (1-4C)haloalkyl, (1-4C)haloalkoxy, amino,             (1-4C)aminoalkyl, cyano, hydroxy, carboxy, carbamoyl,             sulphamoyl, mercapto, ureido, NR_(c)R_(d), OR_(c),             C(O)R_(c), C(O)OR_(c), OC(O)R_(c), C(O)N(R_(d))R_(c),             N(R_(d))C(O)R_(c), S(O)_(y)R_(c) (where y is 0, 1 or 2),             SO₂N(R_(d))R_(c), N(R_(d))SO₂R_(c), Si(R_(d))(R_(c))R_(e) or             (CH₂)_(z)NR_(d)R_(c) (where z is 1, 2 or 3); wherein R_(c),             R_(d) and R_(e) are each independently selected from             hydrogen, (1-6C)alkyl or (3-6C)cycloalkyl; or R_(c) and             R_(d) can be linked such that, together with the nitrogen             atom to which they are attached, they form a 4-7 membered             heterocyclic ring which is optionally substituted by one or             more substituents selected from (1-4C)alkyl, halo,             (1-4C)haloalkyl, (1-4C)haloalkoxy, (1-4C)alkoxy,             (1-4C)alkylamino, amino, cyano or hydroxy;

-   (7) R₁ is selected from hydrogen, (1-4C)haloalkyl, (1-4C)haloalkoxy     or a group of the formula:

-L-Y-Q

-   -   wherein:         -   L is absent or (1-3C)alkylene optionally substituted by one             or more substituents selected from (1-2C)alkyl or oxo;         -   Y is absent or C(O), C(O)O, OC(O), C(O)N(R_(a)) or             N(R_(a))C(O), wherein R_(a) and R_(b) are each independently             selected from hydrogen or (1-4C)alkyl; and         -   Q is hydrogen, (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl,             aryl, (3-10C)cycloalkyl, (3-10C)cycloalkenyl, heteroaryl or             heterocyclyl;     -   wherein Q is optionally further substituted by one or more         substituent groups independently selected from (1-4C)alkyl,         halo, (1-4C)haloalkyl, (1-4C)haloalkoxy, amino,         (1-4C)aminoalkyl, cyano, hydroxy, carboxy, carbamoyl,         sulphamoyl, mercapto, ureido, NR_(c)R_(d), OR_(c), C(O)R_(c),         C(O)OR_(c), OC(O)R_(c), C(O)N(R_(d))R_(c), N(R_(d))C(O)R_(c),         S(O)_(y)R_(c) (where y is 0, 1 or 2), SO₂N(R_(d))R_(c),         N(R_(d))SO₂R_(c), Si(R_(d))(R_(c))R_(e) or (CH₂)_(z)NR_(d)R_(c)         (where z is 1, 2 or 3); wherein R_(c), R_(d) and R_(e) are each         independently selected from hydrogen, (1-6C)alkyl or         (3-6C)cycloalkyl;

-   (8) R₁ is selected from hydrogen, (1-4C)haloalkyl, (1-4C)haloalkoxy,     (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl, aryl, (3-10C)cycloalkyl,     (3-10C)cycloalkenyl, heteroaryl or heterocyclyl; wherein each of     said substituents is optionally further substituted by one or more     substituent groups independently selected from (1-4C)alkyl, halo,     (1-4C)haloalkyl, (1-4C)haloalkoxy, amino, (1-4C)aminoalkyl, cyano,     hydroxy, carboxy, carbamoyl, sulphamoyl, mercapto, ureido,     NR_(c)R_(d), OR_(c), C(O)R_(c), C(O)OR_(c), OC(O)R_(c),     C(O)N(R_(d))R_(c), N(R_(d))C(O)R_(c), S(O)_(y)R_(c) (where y is 0, 1     or 2), SO₂N(R_(d))R_(c), N(R_(d))SO₂R_(c), Si(R_(d))(R_(c))R_(e) or     (CH₂)_(z)NR_(d)R_(c) (where z is 1, 2 or 3); wherein R_(c), R_(d)     and R_(e) are each independently selected from hydrogen, (1-6C)alkyl     or (3-6C)cycloalkyl;

-   (9) R₁ is selected from hydrogen, (1-4C)haloalkyl, (1-4C)haloalkoxy,     (1-6C)alkyl, (3-10C)cycloalkyl or heterocyclyl; wherein each of said     substituents is optionally further substituted by one or more     substituent groups independently selected from (1-4C)alkyl, halo,     (1-4C)haloalkyl, (1-4C)haloalkoxy, amino, (1-4C)aminoalkyl, cyano,     hydroxy, carboxy, carbamoyl, sulphamoyl, mercapto, ureido,     NR_(c)R_(d), OR_(c) or Si(R_(d))(R_(c))R_(e); wherein R_(c), R_(d)     and R_(e) are each independently selected from hydrogen or     (1-6C)alkyl;

-   (10) R₁ is selected from hydrogen, (1-6C)alkyl or (3-10C)cycloalkyl;     wherein each of said substituents is optionally further substituted     by one or more substituent groups independently selected from     (1-4C)alkyl, halo, amino, (1-4C)aminoalkyl, cyano, hydroxy, carboxy,     NR_(c)R_(d), OR_(c) or Si(R_(d))(R_(c))R_(e); wherein R_(c), R_(d)     and R_(e) are each independently selected from hydrogen or     (1-4C)alkyl;

-   (11) R₁ is selected from hydrogen, (1-6C)alkyl or (3-6C)cycloalkyl;     wherein each of said substituents is optionally further substituted     by one or more substituent groups independently selected from     (1-4C)alkyl, OR_(c) or Si(R_(d))(R_(c))R_(e); wherein R_(c), R_(d)     and R_(e) are each independently selected from hydrogen or     (1-2C)alkyl;

-   (12) R₁ is tert-butyl;

-   (13) R_(1a) and R_(1b) are each selected from H, (1-4C)alkyl, halo,     (1-4C)haloalkyl, (1-4C)haloalkoxy, (1-4C)alkoxy, (1-4C)alkylamino,     amino, cyano or hydroxy;

-   (14) R_(1a) and R_(1b) are each selected from H, (1-4C)alkyl, halo,     (1-4C)haloalkyl, (1-4C)alkoxy, amino, cyano or hydroxy;

-   (15) R_(1a) and R_(1b) are each selected from H or (1-4C)alkyl;

-   (16) R_(1a) and R_(1b) are each H;

-   (17) W is selected from O or S;

-   (18) W is O;

-   (19) bonds a, b, c and d are all double bonds;

-   (20) bonds a, b, c and d are all single bonds;

-   (21) X₁ and X₂ are each independently selected from N or CR_(j) when     bond a is a double bond, or NR_(k) or CR_(j)R_(k) when bond a is a     single bond;     -   wherein         -   R_(j) is selected from hydrogen, halo, (1-4C)alkyl,             (1-4C)alkoxy, amino, (1-4C)alkylamino, (1-4C)dialkylamino,             cyano, (2C)alkynyl, wherein said (1-4C)alkyl is optionally             substituted by one or more substituents selected from amino,             hydroxy, (1-2C)alkoxy or halo;         -   R_(k) and R_(j) are independently selected from hydrogen or             (1-4C)alkyl;

-   (22) X₁ and X₂ are each independently selected from N or CR_(j) when     bond a is a double bond, or NR_(k) or CR_(j)R_(k) when bond a is a     single bond;     -   wherein         -   R_(j) is selected from hydrogen, halo, (1-4C)alkyl,             (1-4C)alkoxy, amino, (1-4C)alkylamino, (1-4C)dialkylamino,             cyano, (2C)alkynyl; and         -   R_(k) and R_(j) are independently selected from hydrogen or             (1-4C)alkyl;

-   (23) X₁ and X₂ are each independently selected from N or CR_(j) and     bond a is a double bond, wherein R_(j) is selected from hydrogen,     halo, (1-4C)alkyl or amino;

-   (24) X₁ and X₂ are CR_(j) and bond a is a double bond, wherein R_(j)     is selected from hydrogen, halo or (1-4C)alkyl;

-   (25) X₁ and X₂ are CH and bond a is a double bond;

-   (26) X₃ is selected from N or CR_(l) when bond b is a double bond,     or NR_(m) or CR_(l)R_(m) when bond b is a single bond;     -   wherein         -   R_(l) is selected from hydrogen, halo, (1-4C)alkyl,             (1-4C)alkoxy, amino, (1-4C)alkylamino, (1-4C)dialkylamino,             cyano, (2C)alkynyl, wherein said (1-4C)alkyl is optionally             substituted by one or more substituents selected from amino,             hydroxy, (1-2C)alkoxy or halo; and         -   R_(l) and R_(m) are independently selected from hydrogen or             (1-4C)alkyl;

-   (27) X₃ is selected from N or CR_(l) when bond b is a double bond,     or NR_(m) or CR_(l)R_(m) when bond b is a single bond;     -   wherein         -   R_(l) is selected from hydrogen, halo, (1-4C)alkyl,             (1-4C)alkoxy, amino, (1-4C)alkylamino, (1-4C)dialkylamino,             cyano, (2C)alkynyl; and         -   R_(l) and R_(m) are independently selected from hydrogen or             (1-4C)alkyl;

-   (28) X₃ is selected from N or CR_(l) and bond b is a double bond,     wherein R_(l) is selected from hydrogen, halo, (1-4C)alkyl or amino;

-   (29) X₃ is CR_(l) and bond b is a double bond, wherein R_(l) is     selected from hydrogen, halo, (1-4C)alkyl or amino;

-   (30) X₃ is CH and bond b is a double bond;

-   (31) X₄ is selected from N or CR_(n) when bond d is a double bond,     or NR_(o) or CR_(n)R_(o) when bond d is a single bond;     -   wherein         -   R_(n) is selected from hydrogen, halo, (1-4C)alkyl,             (1-4C)alkoxy, amino, (1-4C)alkylamino, (1-4C)dialkylamino,             cyano, (2C)alkynyl, wherein said (1-4C)alkyl is optionally             substituted by one or more substituents selected from amino,             hydroxy, (1-2C)alkoxy or halo;         -   R_(n) and R_(o) are independently selected from hydrogen or             (1-4C)alkyl; and

-   (32) X₄ is selected from N or CR_(n) when bond d is a double bond,     or NR_(o) or CR_(n)R_(o) when bond d is a single bond;     -   wherein         -   R_(n) is selected from hydrogen, halo, (1-4C)alkyl,             (1-4C)alkoxy, amino, (1-4C)alkylamino, (1-4C)dialkylamino,             cyano, (2C)alkynyl; and         -   R_(n) and R_(o) are independently selected from hydrogen or             (1-4C)alkyl;

-   (33) X₄ is selected from N or CR_(n) and bond d is a double bond,     wherein R_(n) is selected from hydrogen, halo, (1-4C)alkyl,     (1-4C)alkoxy, amino, (1-4C)alkylamino, (1-4C)dialkylamino or cyano,     (2C)alkynyl;

-   (34) X₄ is CR_(n) and bond d is a double bond, wherein R_(n) is     selected from hydrogen, halo, (1-4C)alkyl or amino;

-   (35) R₂ is selected from hydrogen, (1-4C)alkyl or a group of the     formula:

-L₂-Y₂-Q₂

-   -   wherein:         -   L₂ is absent or (1-3C)alkylene optionally substituted by one             or more substituents selected from (1-2C)alkyl or oxo;         -   Y₂ is absent or C(O), C(O)O, C(O)N(R_(p)), wherein R_(p) is             selected from hydrogen or (1-4C)alkyl; and         -   Q₂ is hydrogen, (1-6C)alkyl, aryl, (3-8C)cycloalkyl,             heteroaryl or heterocyclyl; wherein Q₂ is optionally further             substituted by one or more substituent groups independently             selected from (1-4C)alkyl, halo, (1-4C)haloalkyl,             (1-4C)haloalkoxy, amino, cyano, hydroxy, NR_(q)R_(r),             OR_(q), wherein R_(q) and R_(r) are each independently             selected from hydrogen or (1-4C)alkyl;

-   (36) R₂ is selected from hydrogen, (1-4C)alkyl or a group of the     formula:

—Y₂-Q₂

-   -   wherein:         -   Y₂ is absent or C(O), C(O)O, C(O)N(R_(p)), wherein R_(p) is             selected from hydrogen or (1-4C)alkyl; and         -   Q₂ is hydrogen, (1-6C)alkyl, aryl, (3-8C)cycloalkyl,             heteroaryl or heterocyclyl; wherein Q₂ is optionally further             substituted by one or more substituent groups independently             selected from (1-4C)alkyl, halo, (1-4C)haloalkyl,             (1-4C)haloalkoxy, amino, cyano, hydroxy, NR_(q)R_(r),             OR_(q), wherein R_(q) and R_(r) are each independently             selected from hydrogen or (1-4C)alkyl;

-   (37) R₂ is selected from hydrogen, (1-4C)alkyl or a group of the     formula:

—Y₂-Q₂

-   -   wherein:         -   Y₂ is C(O)N(R_(p)), wherein R_(p) is selected from hydrogen             or (1-4C)alkyl; and         -   Q₂ is (1-6C)alkyl, aryl, (3-8C)cycloalkyl, heteroaryl or             heterocyclyl; wherein Q₂ is optionally further substituted             by one or more substituent groups independently selected             from (1-4C)alkyl, halo, (1-4C)haloalkyl, (1-4C)haloalkoxy,             amino, cyano or hydroxy;

-   (38) R₂ is selected from hydrogen or (1-4C)alkyl;

-   (39) R₂ is hydrogen;

-   (40) R₃ is selected from a group of the formula:

—Y₃-Q₃

-   -   wherein:         -   Y₃ is C(O), C(O)N(R_(s)), N(R_(s))(O)C, C(O)OR_(s),             OC(O)CR_(s), wherein R_(s) is selected from hydrogen or             (1-2C)alkyl; and         -   Q₃ is hydrogen, (1-6C)alkyl, (1-6C)alkoxy, aryl,             aryl(1-2C)alkyl, (3-8C)cycloalkyl, (3-8C)cycloalkenyl,             heteroaryl or heterocyclyl; wherein Q₃ is optionally further             substituted by one or more substituent groups independently             selected from (1-4C)alkyl, halo, (1-4C)haloalkyl,             (1-4C)haloalkoxy, amino, cyano, hydroxy, carboxy, carbamoyl,             sulphamoyl, NR_(t)R_(u), OR_(t), wherein R_(t) and R_(u) are             each independently selected from hydrogen, (1-4C)alkyl or             (3-6C)cycloalkyl; or Q₃ is optionally substituted by a group             of the formula:

-L₄-L_(Q4)-Z₄

-   -   -   -   wherein:             -   L₄ is absent or (1-3C)alkylene optionally substituted by                 one or more substituents selected from (1-2C)alkyl or                 oxo;             -   L_(Q4) is absent or selected from or O, N(R_(v)), C(O),                 C(O)O, OC(O), C(O)N(R_(v)), N(R_(v))C(O), S(O)₂N(R_(v)),                 or N(R_(v))SO₂, wherein R_(v) and R_(w) are each                 independently selected from hydrogen or (1-2C)alkyl; and             -   Z₄ is hydrogen, (1-6C)alkyl, aryl, aryl(1-2C)alkyl,                 (3-8C)cycloalkyl, (3-8C)cycloalkenyl, heteroaryl or                 heterocyclyl; wherein Z₄ is optionally substituted by                 one or more substituents selected from (1-4C)alkyl,                 halo, (1-4C)haloalkyl, (1-4C)haloalkoxy, (1-4C)alkoxy,                 (1-4C)alkylamino, amino, cyano, hydroxy, carboxy,                 carbamoyl, sulphamoyl, mercapto, ureido, aryl,                 heteroaryl, heterocycyl, (3-6C)cycloalkyl, NR_(x)R_(y),                 OR_(x), C(O)R_(x), C(O)OR_(x), OC(O)R_(x),                 C(O)N(R_(y))R_(x), N(R_(y))C(O)R_(x), S(O)_(y)R_(x)                 (where y is 0, 1 or 2), SO₂N(R_(y))R_(x),                 N(R_(y))SO₂R_(x) or (CH₂)_(z)NR_(x)R_(y) (where z is 1,                 2 or 3); wherein R_(x) and R_(y) are each independently                 selected from hydrogen, (1-4C)alkyl or (3-6C)cycloalkyl;

-   (41) R₃ is selected from a group of the formula:

—Y₃-Q₃

-   -   wherein:         -   Y₃ is C(O)N(R_(s)), wherein R_(s) is selected from hydrogen             or (1-2C)alkyl; and         -   Q₃ is hydrogen, (1-6C)alkyl, (1-6C)alkoxy, aryl,             aryl(1-2C)alkyl, (3-8C)cycloalkyl, (3-8C)cycloalkenyl,             heteroaryl or heterocyclyl; wherein Q₃ is optionally further             substituted by one or more substituent groups independently             selected from (1-4C)alkyl, halo, (1-4C)haloalkyl,             (1-4C)haloalkoxy, amino, cyano, hydroxy, carboxy, carbamoyl,             sulphamoyl, NR_(t)R_(u), OR_(t), wherein R_(t) and R_(u) are             each independently selected from hydrogen, (1-4C)alkyl or             (3-6C)cycloalkyl; or Q₃ is optionally substituted by a group             of the formula:

-L₄-L_(Q4)-Z₄

-   -   -   wherein:             -   L₄ is absent or (1-3C)alkylene optionally substituted by                 one or more substituents selected from (1-2C)alkyl or                 oxo;             -   L_(Q4) is absent or selected from or O, S, SO, SO₂,                 N(R_(v)), C(O), C(O)O, OC(O), C(O)N(R_(v)),                 N(R_(v))C(O), N(R_(w))C(O)N(R_(v)), N(R_(v))C(O)O,                 OC(O)N(R_(v)), S(O)₂N(R_(v)), or N(R_(v))SO₂, wherein                 R_(v) and R_(w) are each independently selected from                 hydrogen or (1-2C)alkyl; and             -   Z₄ is hydrogen, (1-6C)alkyl, aryl, aryl(1-2C)alkyl,                 (3-8C)cycloalkyl, (3-8C)cycloalkenyl, heteroaryl or                 heterocyclyl;

    -   wherein Z₄ is optionally substituted by one or more substituents         selected from (1-4C)alkyl, halo, (1-4C)haloalkyl,         (1-4C)haloalkoxy, (1-4C)alkoxy, (1-4C)alkylamino, amino, cyano,         hydroxy, carboxy, carbamoyl, sulphamoyl, mercapto, ureido, aryl,         heteroaryl, heterocycyl, (3-6C)cycloalkyl, NR_(x)R_(y), OR_(x),         C(O)R_(x), C(O)OR_(x), OC(O)R_(x), C(O)N(R_(y))R_(x),         N(R_(y))C(O)R_(x), S(O)_(y)R_(x) (where y is 0, 1 or 2),         SO₂N(R_(y))R_(x), N(R_(y))SO₂R_(x) or (CH₂)_(z)NR_(x)R_(y)         (where z is 1, 2 or 3); wherein R_(x) and R_(y) are each         independently selected from hydrogen, (1-4C)alkyl or         (3-6C)cycloalkyl;

-   (42) R₃ is selected from a group of the formula:

—Y₃-Q₃

-   -   wherein:         -   Y₃ is C(O)NH; and         -   Q₃ is hydrogen, (1-6C)alkyl, (1-6C)alkoxy, aryl,             aryl(1-2C)alkyl, (3-8C)cycloalkyl, (3-8C)cycloalkenyl,             heteroaryl or heterocyclyl; wherein Q₃ is optionally further             substituted by one or more substituent groups independently             selected from (1-4C)alkyl, halo, (1-4C)haloalkyl,             (1-4C)haloalkoxy, amino, cyano, hydroxy, carboxy, carbamoyl,             sulphamoyl, NR_(t)R_(u), OR_(t), wherein R_(t) and R_(u) are             each independently selected from hydrogen, (1-4C)alkyl or             (3-6C)cycloalkyl; or Q₃ is optionally substituted by a group             of the formula:

-L₄-L_(Q4)-Z₄

-   -   -   wherein:             -   L₄ is absent or (1-3C)alkylene optionally substituted by                 one or more substituents selected from (1-2C)alkyl or                 oxo;             -   L_(Q4) is absent or selected from or O, N(R_(v)), C(O),                 C(O)O, OC(O), C(O)N(R_(v)), N(R_(v))C(O), S(O)₂N(R_(v)),                 or N(R_(v))SO₂, wherein R_(v) and R_(w) are each                 independently selected from hydrogen or (1-2C)alkyl; and             -   Z₄ is hydrogen, (1-6C)alkyl, aryl, aryl(1-2C)alkyl,                 (3-8C)cycloalkyl, (3-8C)cycloalkenyl, heteroaryl or                 heterocyclyl; wherein Z₄ is optionally substituted by                 one or more substituents selected from (1-4C)alkyl,                 halo, (1-4C)haloalkyl, (1-4C)haloalkoxy, (1-4C)alkoxy,                 (1-4C)alkylamino, amino, cyano, hydroxy, carboxy,                 carbamoyl, sulphamoyl, mercapto, ureido, aryl,                 heteroaryl, heterocycyl, (3-6C)cycloalkyl, NR_(x)R_(y),                 OR_(x); wherein R_(x) and R_(y) are each independently                 selected from hydrogen or (1-4C)alkyl;

-   (43) R₃ is selected from a group of the formula:

—Y₃-Q₃

-   -   wherein:         -   Y₃ is C(O)NH; and         -   Q₃ is hydrogen, (1-6C)alkyl, (1-6C)alkoxy, aryl,             aryl(1-2C)alkyl, (3-8C)cycloalkyl, (3-8C)cycloalkenyl,             heteroaryl or heterocyclyl; wherein Q₃ is optionally further             substituted by one or more substituent groups independently             selected from (1-4C)alkyl, halo, (1-4C)haloalkyl,             (1-4C)haloalkoxy, amino, cyano, hydroxy, carboxy, carbamoyl,             sulphamoyl, NR_(t)R_(u), OR_(t), wherein R_(t) and R_(u) are             each independently selected from hydrogen, (1-4C)alkyl or             (3-6C)cycloalkyl; or Q₃ is optionally substituted by a group             of the formula:

-L₄-L_(Q4)-Z₄

-   -   -   wherein:             -   L₄ is absent or (1-3C)alkylene optionally substituted by                 one or more substituents selected from (1-2C)alkyl;             -   L_(Q4) is absent or selected from or O, N(R_(v)),                 wherein R_(v) is selected from hydrogen or (1-2C)alkyl;                 and             -   Z₄ is hydrogen, (1-6C)alkyl, (3-8C)cycloalkyl; wherein                 Z₄ is optionally substituted by one or more substituents                 selected from (1-4C)alkyl, halo, (1-4C)haloalkyl,                 (1-4C)haloalkoxy, (1-4C)alkoxy, (1-4C)alkylamino, amino,                 cyano, hydroxy, (3-6C)cycloalkyl, NR_(x)R_(y), OR_(x);                 wherein R_(x) and R_(y) are each independently selected                 from hydrogen or (1-4C)alkyl;

-   (44) R₃ is selected from a group of the formula:

—Y₃-Q₃

-   -   wherein:         -   Y₃ is C(O)NH; and         -   Q₃ is hydrogen, (1-6C)alkyl, (1-6C)alkoxy, aryl,             aryl(1-2C)alkyl, (3-8C)cycloalkyl, heteroaryl or             heterocyclyl; wherein Q₃ is optionally further substituted             by one or more substituent groups independently selected             from (1-4C)alkyl, halo, (1-4C)haloalkyl, amino, cyano,             hydroxy, NR_(t)R_(u), OR_(t), wherein R_(t) and R_(u) are             each independently selected from hydrogen or (1-4C)alkyl; or             Q₃ is optionally substituted by a group of the formula:

-L₄-L_(Q4)-Z₄

-   -   -   wherein:             -   L₄ is absent or (1-2C)alkylene;             -   L_(Q4) is absent or selected from or O; and             -   Z₄ is hydrogen, (1-6C)alkyl, (3-8C)cycloalkyl; wherein                 Z₄ is optionally substituted by one or more substituents                 selected from (1-4C)alkyl, halo, (1-4C)haloalkyl,                 (1-4C)alkoxy, amino, hydroxy, (3-6C)cycloalkyl,                 NR_(x)R_(y), OR_(x); wherein R_(x) and R_(y) are each                 independently selected from hydrogen or (1-4C)alkyl.

Suitably, a heteroaryl or heterocyclyl group as defined herein is a monocyclic heteroaryl or heterocyclyl group comprising one, two or three heteroatoms selected from N, O or S.

Suitably, a heteroaryl is a 5- or 6-membered heteroaryl ring comprising one, two or three heteroatoms selected from N, O or S.

Suitably, a heterocyclyl group is a 4-, 5- or 6-membered heterocyclyl ring comprising one, two or three heteroatoms selected from N, O or S. Most suitably, a heterocyclyl group is a 5-, 6- or 7-membered ring comprising one, two or three heteroatoms selected from N, O or S [e.g. morpholinyl (e.g. 4-morpholinyl), pyridinyl, piperazinyl, homopiperazinyl or pyrrolidinonyl].

Suitably an aryl group is phenyl.

Suitably, HET is as defined in any one of paragraphs (1) to (3). Most suitably, HET is as defined in paragraph (3).

Suitably, R₁ is as defined in any one of paragraphs (4) to (12). More suitably, R₁ is as defined in any one of paragraphs (8) to (12). Most suitably, R₁ is as defined in paragraph (12).

Suitably R_(1a) and R_(1b) are as defined in any one of paragraphs (13) to (16). Most suitably, R_(1a) and R_(1b) are as defined in paragraph (16).

Suitably, W is as defined in any one of paragraphs (17) to (18). Most suitably, W is as defined in paragraph (18).

Suitably, bonds a, b, c and d are as defined in any one of paragraphs (19) to (20).

Suitably, bonds a, b, c and d are as defined in paragraph (19).

Suitably, X₁ and X₂ are as defined in any one of paragraphs (21) to (25). Most suitably, X₁ and X₂ are as defined in paragraph (25).

Suitably, X₃ is as defined in any one of paragraphs (26) to (30). Most suitably, X₃ is as defined in paragraph (30).

Suitably, X₄ is as defined in any one of paragraphs (31) to (34). Most suitably, X₄ is as defined in paragraph (34).

Suitably, R₂ is as defined in any one of paragraphs (35) to (39). More suitably, R₂ is as defined in any one of paragraphs (37) to (39). Most suitably, R2 is as defined in paragraph (39).

Suitably, R₃ is as defined in any one of paragraphs (40) to (44). Most suitably, R₃ is as defined in paragraph (44).

In a particular group of compounds of the invention, the compounds have the structural formula Ia (a sub-definition of formula (I)) shown below, or a pharmaceutically acceptable salt, hydrate and/or solvate thereof:

wherein HET, R₁, R_(1a), R_(1b), bonds a, b, c and d, X₁, X₂, X₃, X₄, R₂, Q₃ and R₅ each have any one of the meanings defined herein.

In an embodiment of the compounds of formula Ia:

HET is as defined in any one of paragraphs (1) to (3) above;

R₁ is as defined in any one of paragraphs (4) to (12) above;

R_(1a) and R_(1b) are as defined in any one of paragraphs (13) to (16) above;

bonds a, b, c and d are as defined in any one of paragraphs (19) to (20) above;

X₁ and X₂ are as defined in any one of paragraphs (21) to (25) above;

X₃ is as defined in any one of paragraphs (26) to (30) above;

X₄ is as defined in any one of paragraphs (31) to (34) above;

R₂ is as defined in any one of paragraphs (35) to (39) above;

R₅ is as defined in any one of paragraphs (40) to (41) above; and

Q₃ is as defined in any one of paragraphs (40) to (44).

In another embodiment of the compounds of formula Ia:

HET is as defined in paragraph (3) above;

R₁ is as defined in paragraph (12) above;

R_(1a) and R_(1b) are as defined in paragraph (16) above;

bonds a, b, c and d are as defined in paragraph (20) above;

X₁ and X₂ are as defined in paragraph (25) above;

X₃ is as defined in paragraph (30) above;

X₄ is as defined in paragraph (34) above;

R₂ is as defined in paragraph (39) above; and

R₃ is as defined in paragraph (44) above.

In a particular group of compounds of the invention, the compounds have the structural formula Ib (a sub-definition of formula (I)) shown below, or a pharmaceutically acceptable salt, hydrate and/or solvate thereof:

wherein R₁, bonds a, b, c and d, X₁, X₂, X₃, X₄, R₂, Q₃ and R₅ each have any one of the meanings defined herein.

In an embodiment of the compounds of formula Ib:

R₁ is as defined in any one of paragraphs (4) to (12) above;

bonds a, b, c and d are as defined in any one of paragraphs (19) to (20) above;

X₁ and X₂ are as defined in any one of paragraphs (21) to (25) above;

X₃ is as defined in any one of paragraphs (26) to (30) above;

X₄ is as defined in any one of paragraphs (31) to (34) above;

R₂ is as defined in any one of paragraphs (35) to (39) above; and

R₅ is as defined in any one of paragraphs (40) to (41) above;

Q₃ is as defined in any one of paragraphs (40) to (44).

In another embodiment of the compounds of formula Ib:

R₁ is as defined in paragraph (12) above;

bonds a, b, c and d are as defined in paragraph (20) above;

X₁ and X₂ are as defined in paragraph (25) above;

X₃ is as defined in paragraph (30) above;

X₄ is as defined in paragraph (34) above;

R₂ is as defined in paragraph (39) above;

R₅ is as defined in paragraph (41) above; and

Q₃ is as defined in paragraph (44) above.

In a particular group of compounds of the invention, the compounds have the structural formula Ic (a sub-definition of formula (I)) shown below, or a pharmaceutically acceptable salt, hydrate and/or solvate thereof:

wherein R₁, X₁, X₂, X₃, X₄, R₂, Q₃ and R₅ each have any one of the meanings defined herein.

In an embodiment of the compounds of formula Ic:

R₁ is as defined in any one of paragraphs (4) to (12) above;

X₁ and X₂ are as defined in any one of paragraphs (23) to (25) above;

X₃ is as defined in any one of paragraphs (28) to (30) above;

X₄ is as defined in any one of paragraphs (33) to (34) above;

R₂ is as defined in any one of paragraphs (35) to (39) above;

R₅ is as defined in any one of paragraphs (40) to (41) above; and

Q₃ is as defined in any one of paragraphs (40) to (44).

In another embodiment of the compounds of formula Ic:

R₁ is as defined in paragraph (12) above;

X₁ and X₂ are as defined in paragraph (25) above;

X₃ is as defined in paragraph (30) above;

X₄ is as defined in paragraph (34) above;

R₂ is as defined in paragraph (39) above;

R₅ is as defined in paragraph (41) above; and

Q₃ is as defined in paragraph (44) above.

In a particular group of compounds of the invention, the compounds have the structural formula Id (a sub-definition of formula (I)) shown below, or a pharmaceutically acceptable salt, hydrate and/or solvate thereof:

wherein R₁, X₄, R₂ and Q₃ each have any one of the meanings defined herein.

In an embodiment of the compounds of formula Id:

R₁ is as defined in any one of paragraphs (4) to (12) above;

X₄ is as defined in any one of paragraphs (33) to (34) above;

R₂ is as defined in any one of paragraphs (35) to (39) above; and

Q₃ is as defined in any one of paragraphs (40) to (44) above.

In another embodiment of the compounds of formula Id:

R₁ is as defined in paragraph (12) above;

X₄ is as defined in paragraph (34) above;

R₂ is as defined in paragraph (39) above; and

Q₃ is as defined in paragraph (44) above.

Particular compounds of the present invention include any of the compounds exemplified in the present application, or a pharmaceutically acceptable salt or solvate thereof, and, in particular, any of the following:

-   6-(4-Amino-1-cyclopropyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-methyl-1H-indole-2-carboxamide; -   6-(4-Amino-1-ethyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-methyl-1H-indole-2-carboxamide; -   6-(4-Amino-1-isopropyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-methyl-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2,5-dimethylpyrazol-3-yl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N,3-dimethyl-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-3-fluoro-N-methyl-1H-indole-2-carboxamide; -   6-(4-Amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-cyclobutyl-1H-indole-2-carboxamide; -   6-(4-Amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-N-ethyl-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-cyclopropyl-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-methyl-1H-indole-2-carboxamide; -   6-(4-Amino-1-isopropyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(1,3,4-thiadiazol-2-yl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-isopropyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(1-methylpyrazol-3-yl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-isopropyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-thiazol-2-yl-1H-indole-2-carboxamide; -   6-(4-Amino-1-isopropyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-ethoxy-1H-indole-2-carboxamide; -   6-(4-Amino-1-isopropyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2-fluoroethyl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-isopropyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-cyclopropyl-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-3-chloro-N-methyl-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-[1-(2-hydroxyethyl)pyrazol-3-yl]-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(4-pyridyl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(3-pyridyl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-[1-(2-fluoroethyl)pyrazol-3-yl]-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-[1-(2-methoxyethyl)pyrazol-3-yl]-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(1-ethylpyrazol-3-yl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(4-methylthiazol-2-yl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-isoxazol-4-yl-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-thiazol-5-yl-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(3-thienyl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(1,2,4-thiadiazol-5-yl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(5-methyl-1,3,4-thiadiazol-2-yl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2-hydroxyethyl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-phenyl-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2-methylpyrazol-3-yl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2-methoxyethoxy)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(1-methylpyrazol-3-yl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(1,3,4-thiadiazol-2-yl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(cyclopropylmethoxy)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-ethoxy-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2,2-difluoroethyl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2,2,2-trifluoroethyl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(cyclopropylmethyl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-N-phenethyl-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-benzyl-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-isobutyl-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2-fluoroethyl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-methoxy-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-propyl-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2-methoxyethyl)-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-butyl-1H-indole-2-carboxamide; -   6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-thiazol-2-yl-1H-indole-2-carboxamide; -   6-(4-amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-isopropyl-1H-indole-2-carboxamide; -   6-[4-amino-1-(3-hydroxy-3-methyl-cyclopentyl)pyrazolo[3,4-d]pyrimidin-3-yl]-N-methyl-1H-indole-2-carboxamide; -   6-(4-amino-1-isopropyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N,3-dimethyl-1H-indole-2-carboxamide; -   6-[4-amino-1-(3-methoxypropyl)pyrazolo[3,4-d]pyrimidin-3-yl]-N-methyl-1H-indole-2-carboxamide; -   6-(4-amino-1-cyclobutyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-methyl-1H-indole-2-carboxamide;     or -   tert-butyl     3-[4-amino-3-[2-(methylcarbamoyl)-1H-indol-6-yl]pyrazolo[3,4-d]pyrimidin-1-yl]azetidine-1-carboxylate.

The various functional groups and substituents making up the compounds of the formula (I) are typically chosen such that the molecular weight of the compound of the formula (I) does not exceed 1000. More usually, the molecular weight of the compound will be less than 900, for Example less than 800, or less than 750, or less than 700, or less than 650. More preferably, the molecular weight is less than 600 and, for Example, is 550 or less.

A suitable pharmaceutically acceptable salt of a compound of the invention is, for Example, an acid-addition salt of a compound of the invention which is sufficiently basic, for Example, an acid-addition salt with, for Example, an inorganic or organic acid, for Example hydrochloric, hydrobromic, sulfuric, phosphoric, trifluoroacetic, formic, citric methane sulfonate or maleic acid. In addition, a suitable pharmaceutically acceptable salt of a compound of the invention which is sufficiently acidic is an alkali metal salt, for Example a sodium or potassium salt, an alkaline earth metal salt, for Example a calcium or magnesium salt, an ammonium salt or a salt with an organic base which affords a pharmaceutically acceptable cation, for Example a salt with methylamine, dimethylamine, trimethylamine, piperidine, morpholine or tris-(2-hydroxyethyl)amine.

Compounds that have the same molecular formula but differ in the nature or sequence of bonding of their atoms or the arrangement of their atoms in space are termed “isomers”. Isomers that differ in the arrangement of their atoms in space are termed “stereoisomers”. Stereoisomers that are not mirror images of one another are termed “diastereomers” and those that are non-superimposable mirror images of each other are termed “enantiomers”. When a compound has an asymmetric center, for Example, it is bonded to four different groups, a pair of enantiomers is possible. An enantiomer can be characterized by the absolute configuration of its asymmetric center and is described by the R- and S-sequencing rules of Cahn and Prelog, or by the manner in which the molecule rotates the plane of polarized light and designated as dextrorotatory or levorotatory (i.e., as (+) or (−)-isomers respectively). A chiral compound can exist as either individual enantiomer or as a mixture thereof. A mixture containing equal proportions of the enantiomers is called a “racemic mixture”.

The compounds of this invention may possess one or more asymmetric centers; such compounds can therefore be produced as individual (R)- or (S)-stereoisomers or as mixtures thereof. Unless indicated otherwise, the description or naming of a particular compound in the specification and claims is intended to include both individual enantiomers and mixtures, racemic or otherwise, thereof. The methods for the determination of stereochemistry and the separation of stereoisomers are well-known in the art (see discussion in Chapter 4 of “Advanced Organic Chemistry”, 4th edition J. March, John Wiley and Sons, New York, 2001), for Example by synthesis from optically active starting materials or by resolution of a racemic form. Some of the compounds of the invention may have geometric isomeric centres (E- and Z-isomers). It is to be understood that the present invention encompasses all optical, diastereoisomers and geometric isomers and mixtures thereof that possess antiproliferative activity.

The present invention also encompasses compounds of the invention as defined herein which comprise one or more isotopic substitutions. For Example, H may be in any isotopic form, including 1H, 2H(D), and 3H (T); C may be in any isotopic form, including 12C, 13C, and 14C; and O may be in any isotopic form, including 16O and 18O; and the like.

It is also to be understood that certain compounds of the formula (I) may exist in solvated as well as unsolvated forms such as, for Example, hydrated forms. It is to be understood that the invention encompasses all such solvated forms that possess antiproliferative activity.

It is also to be understood that certain compounds of the formula I may exhibit polymorphism, and that the invention encompasses all such forms that possess antiproliferative activity.

Compounds of the formula I may exist in a number of different tautomeric forms and references to compounds of the formula I include all such forms. For the avoidance of doubt, where a compound can exist in one of several tautomeric forms, and only one is specifically described or shown, all others are nevertheless embraced by formula I. Examples of tautomeric forms include keto-, enol-, and enolate-forms, as in, for Example, the following tautomeric pairs: keto/enol (illustrated below), imine/enamine, amide/imino alcohol, amidine/amidine, nitroso/oxime, thioketone/enethiol, and nitro/aci-nitro.

Compounds of the formula I containing an amine function may also form N-oxides. A reference herein to a compound of the formula I that contains an amine function also includes the N-oxide. Where a compound contains several amine functions, one or more than one nitrogen atom may be oxidised to form an N-oxide. Particular Examples of N-oxides are the N-oxides of a tertiary amine or a nitrogen atom of a nitrogen-containing heterocycle. N-Oxides can be formed by treatment of the corresponding amine with an oxidizing agent such as hydrogen peroxide or a per-acid (e.g. a peroxycarboxylic acid), see for Example Advanced Organic Chemistry, by Jerry March, 4th Edition, Wiley Interscience, pages. More particularly, N-oxides can be made by the procedure of L. W. Deady (Syn. Comm. 1977, 7, 509-514) in which the amine compound is reacted with m-chloroperoxybenzoic acid (mCPBA), for Example, in an inert solvent such as dichloromethane.

The compounds of formula (I) may be administered in the form of a pro-drug which is broken down in the human or animal body to release a compound of the invention. A pro-drug may be used to alter the physical properties and/or the pharmacokinetic properties of a compound of the invention. A pro-drug can be formed when the compound of the invention contains a suitable group or substituent to which a property-modifying group can be attached. Examples of pro-drugs include in vivo cleavable ester derivatives that may be formed at a carboxy group or a hydroxy group in a compound of the formula (I) and in-vivo cleavable amide derivatives that may be formed at a carboxy group or an amino group in a compound of the formula (I).

Accordingly, the present invention includes those compounds of the formula (I) as defined hereinbefore when made available by organic synthesis and when made available within the human or animal body by way of cleavage of a pro-drug thereof. Accordingly, the present invention includes those compounds of the formula I that are produced by organic synthetic means and also such compounds that are produced in the human or animal body by way of metabolism of a precursor compound, that is a compound of the formula (I) may be a synthetically-produced compound or a metabolically-produced compound.

A suitable pharmaceutically acceptable pro-drug of a compound of the formula (I) is one that is based on reasonable medical judgement as being suitable for administration to the human or animal body without undesirable pharmacological activities and without undue toxicity.

Various forms of pro-drug have been described, for Example in the following documents:—

-   a) Methods in Enzymology, Vol. 42, p. 309-396, edited by K. Widder,     et al. (Academic Press, 1985); -   b) Design of Pro-drugs, edited by H. Bundgaard, (Elsevier, 1985); -   c) A Textbook of Drug Design and Development, edited by     Krogsgaard-Larsen and H. Bundgaard, Chapter 5 “Design and     Application of Pro-drugs”, by H. Bundgaard p. 113-191 (1991); -   d) H. Bundgaard, Advanced Drug Delivery Reviews, 8, 1-38 (1992); -   e) H. Bundgaard, et al., Journal of Pharmaceutical Sciences, 77, 285     (1988); -   f) N. Kakeya, et al., Chem. Pharm. Bull., 32, 692 (1984); -   g) T. Higuchi and V. Stella, “Pro-Drugs as Novel Delivery Systems”,     A.C.S. Symposium Series, Volume 14; and -   h) E. Roche (editor), “Bioreversible Carriers in Drug Design”,     Pergamon Press, 1987.

A suitable pharmaceutically acceptable pro-drug of a compound of the formula I that possesses a carboxy group is, for Example, an in vivo cleavable ester thereof. An in vivo cleavable ester of a compound of the formula I containing a carboxy group is, for Example, a pharmaceutically acceptable ester which is cleaved in the human or animal body to produce the parent acid. Suitable pharmaceutically acceptable esters for carboxy include C1-6alkyl esters such as methyl, ethyl and tert-butyl, C1-6alkoxymethyl esters such as methoxymethyl esters, C1-6alkanoyloxymethyl esters such as pivaloyloxymethyl esters, 3-phthalidyl esters, C3-8cycloalkylcarbonyloxy-C1-6alkyl esters such as cyclopentylcarbonyloxymethyl and 1-cyclohexylcarbonyloxyethyl esters, 2-oxo-1,3-dioxolenylmethyl esters such as 5-methyl-2-oxo-1,3-dioxolen-4-ylmethyl esters and C1-6alkoxycarbonyloxy-C1-6alkyl esters such as methoxycarbonyloxymethyl and 1-methoxycarbonyloxyethyl esters.

A suitable pharmaceutically acceptable pro-drug of a compound of the Formula (I) that possesses a hydroxy group is, for Example, an in vivo cleavable ester or ether thereof. An in vivo cleavable ester or ether of a compound of the formula I containing a hydroxy group is, for Example, a pharmaceutically acceptable ester or ether which is cleaved in the human or animal body to produce the parent hydroxy compound. Suitable pharmaceutically acceptable ester forming groups for a hydroxy group include inorganic esters such as phosphate esters (including phosphoramidic cyclic esters). Further suitable pharmaceutically acceptable ester forming groups for a hydroxy group include C1-10alkanoyl groups such as acetyl, benzoyl, phenylacetyl and substituted benzoyl and phenylacetyl groups, C1-10alkoxycarbonyl groups such as ethoxycarbonyl, N,N—(C1-6)2carbamoyl, 2-dialkylaminoacetyl and 2-carboxyacetyl groups. Examples of ring substituents on the phenylacetyl and benzoyl groups include aminomethyl, N-alkylaminomethyl, N,N-dialkylaminomethyl, morpholinomethyl, piperazin-1-ylmethyl and 4-(C1-4alkyl)piperazin-1-ylmethyl. Suitable pharmaceutically acceptable ether forming groups for a hydroxy group include α-acyloxyalkyl groups such as acetoxymethyl and pivaloyloxymethyl groups.

A suitable pharmaceutically acceptable pro-drug of a compound of the formula (I) that possesses a carboxy group is, for Example, an in vivo cleavable amide thereof, for Example an amide formed with an amine such as ammonia, a C1-4alkylamine such as methylamine, a (C1-4alkyl)2amine such as dimethylamine, N-ethyl-N-methylamine or diethylamine, a C1-4alkoxy-C2-4alkylamine such as 2-methoxyethylamine, a phenyl-C1-4alkylamine such as benzylamine and amino acids such as glycine or an ester thereof.

A suitable pharmaceutically acceptable pro-drug of a compound of the formula I that possesses an amino group is, for Example, an in vivo cleavable amide derivative thereof. Suitable pharmaceutically acceptable amides from an amino group include, for Example an amide formed with C1-10alkanoyl groups such as an acetyl, benzoyl, phenylacetyl and substituted benzoyl and phenylacetyl groups. Examples of ring substituents on the phenylacetyl and benzoyl groups include aminomethyl, N-alkylaminomethyl, N,N-dialkylaminomethyl, morpholinomethyl, piperazin-1-ylmethyl and 4-(C1-4alkyl)piperazin-1-ylmethyl.

The in vivo effects of a compound of the formula (I) may be exerted in part by one or more metabolites that are formed within the human or animal body after administration of a compound of the formula (I). As stated hereinbefore, the in vivo effects of a compound of the formula (I) may also be exerted by way of metabolism of a precursor compound (a pro-drug).

Though the present invention may relate to any compound or particular group of compounds defined herein by way of optional, preferred or suitable features or otherwise in terms of particular embodiments, the present invention may also relate to any compound or particular group of compounds that specifically excludes said optional, preferred or suitable features or particular embodiments.

Suitably, the present invention excludes any individual compounds not possessing the biological activity defined herein.

Synthesis

The compounds of the present invention can be prepared by any suitable technique known in the art. Particular processes for the preparation of these compounds are described further in the accompanying Examples.

In the description of the synthetic methods described herein and in any referenced synthetic methods that are used to prepare the starting materials, it is to be understood that all proposed reaction conditions, including choice of solvent, reaction atmosphere, reaction temperature, duration of the experiment and workup procedures, can be selected by a person skilled in the art.

It is understood by one skilled in the art of organic synthesis that the functionality present on various portions of the molecule must be compatible with the reagents and reaction conditions utilised.

It will be appreciated that during the synthesis of the compounds of the invention in the processes defined herein, or during the synthesis of certain starting materials, it may be desirable to protect certain substituent groups to prevent their undesired reaction. The skilled chemist will appreciate when such protection is required, and how such protecting groups may be put in place, and later removed.

For Examples of protecting groups see one of the many general texts on the subject, for Example, ‘Protective Groups in Organic Synthesis’ by Theodora Green (publisher: John Wiley & Sons). Protecting groups may be removed by any convenient method described in the literature or known to the skilled chemist as appropriate for the removal of the protecting group in question, such methods being chosen so as to effect removal of the protecting group with the minimum disturbance of groups elsewhere in the molecule.

Thus, if reactants include, for Example, groups such as amino, carboxy or hydroxy it may be desirable to protect the group in some of the reactions mentioned herein.

By way of Example, a suitable protecting group for an amino or alkylamino group is, for Example, an acyl group, for Example an alkanoyl group such as acetyl, an alkoxycarbonyl group, for Example a methoxycarbonyl, ethoxycarbonyl or t-butoxycarbonyl group, an arylmethoxycarbonyl group, for Example benzyloxycarbonyl, or an aroyl group, for Example benzoyl. The deprotection conditions for the above protecting groups necessarily vary with the choice of protecting group. Thus, for Example, an acyl group such as an alkanoyl or alkoxycarbonyl group or an aroyl group may be removed by, for Example, hydrolysis with a suitable base such as an alkali metal hydroxide, for Example lithium or sodium hydroxide. Alternatively an acyl group such as a tert-butoxycarbonyl group may be removed, for Example, by treatment with a suitable acid as hydrochloric, sulfuric or phosphoric acid or trifluoroacetic acid and an arylmethoxycarbonyl group such as a benzyloxycarbonyl group may be removed, for Example, by hydrogenation over a catalyst such as palladium-on-carbon, or by treatment with a Lewis acid for Example boron tris(trifluoroacetate). A suitable alternative protecting group for a primary amino group is, for Example, a phthaloyl group which may be removed by treatment with an alkylamine, for Example dimethylaminopropylamine, or with hydrazine.

A suitable protecting group for a hydroxy group is, for Example, an acyl group, for Example an alkanoyl group such as acetyl, an aroyl group, for Example benzoyl, or an arylmethyl group, for Example benzyl. The deprotection conditions for the above protecting groups will necessarily vary with the choice of protecting group. Thus, for Example, an acyl group such as an alkanoyl or an aroyl group may be removed, for Example, by hydrolysis with a suitable base such as an alkali metal hydroxide, for Example lithium, sodium hydroxide or ammonia. Alternatively an arylmethyl group such as a benzyl group may be removed, for Example, by hydrogenation over a catalyst such as palladium-on-carbon.

A suitable protecting group for a carboxy group is, for Example, an esterifying group, for Example a methyl or an ethyl group which may be removed, for Example, by hydrolysis with a base such as sodium hydroxide, or for Example a t-butyl group which may be removed, for Example, by treatment with an acid, for Example an organic acid such as trifluoroacetic acid, or for Example a benzyl group which may be removed, for Example, by hydrogenation over a catalyst such as palladium-on-carbon.

Resins may also be used as a protecting group.

The methodology employed to synthesise a compound of formula (I) will vary depending on the nature of HET, X₁, X₂, X₃, X₄, R₂, R₃ and any substituent groups associated therewith. Suitable processes for their preparation are described further in the accompanying Examples.

Once a compound of formula (I) has been synthesised by any one of the processes defined herein, the processes may then further comprise the additional steps of:

(i) removing any protecting groups present; (ii) converting the compound formula (I) into another compound of formula (I); (iii) forming a pharmaceutically acceptable salt, hydrate or solvate thereof; and/or (iv) forming a prodrug thereof.

An Example of (ii) above is when a compound of formula (I) is synthesised and then one or more of the groups of HET, X₁, X₂, X₃, X₄, R₂, R₃, may be further reacted to change the nature of the group and provide an alternative compound of formula (I). For Example, the compound can be reacted to convert any R group into a substituent group other than hydrogen.

The resultant compounds of formula (I) can be isolated and purified using techniques well known in the art.

Biological Activity

The biological assays described in Example 51 herein may be used to measure the pharmacological effects of the compounds of the present invention.

Although the pharmacological properties of the compounds of formula I vary with structural change, as expected, the compounds of the invention were found to be active in the RET assays described in Example 51.

In general, the compounds of the invention demonstrate an IC₅₀ of 1 μM or less in the RET assay described in Example 51, with preferred compounds of the invention demonstrating an IC₅₀ of 200 nM or less and the most preferred compounds of the invention demonstrating an IC₅₀ of 50 nM or less.

Suitably the ratio of RET activity to KDR activity measured in the RET and KDR assays set out in Example 51 herein is greater than 5, more suitably greater than 10, yet more suitably greater than 25, and most suitably greater than 100.

In the RET cell assay described herein in Example 51, the compounds of formula I suitably possess an activity of less than 1 μM, with the preferred compounds demonstrating an activity of 500 nM or less and the most preferred compounds of the invention demonstrating an IC₅₀ of 200 nM or less.

The following compounds were tested but did not exhibit the desired activity in the assays described in Example 51:

-   6-(4-amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic     acid; -   N-ethyl-6-[1-[(1S,3R)-3-hydroxycyclopentyl]-4-(methylamino)pyrazolo[3,4-d]pyrimidin-3-yl]-1H-indole-2-carboxamide; -   6-(4-amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-[5-(trifluoromethyl)-1,3,4-thiadiazol-2-yl]-1H-indole-2-carboxamide; -   6-(4-amino-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-N-methyl-1H-indole-2-carboxamide; -   6-[4-amino-1-(2-hydroxyethyl)pyrazolo[3,4-d]pyrimidin-3-yl]-N-methyl-1H-indole-2-carboxamide; -   6-[4-amino-1-[2-(dimethylamino)-2-oxo-ethyl]pyrazolo[3,4-d]pyrimidin-3-yl]-N-methyl-1H-indole-2-carboxamide;     and -   6-[4-amino-1-[3-(dimethylamino)-3-oxo-propyl]pyrazolo[3,4-d]pyrimidin-3-yl]-N-methyl-1H-indole-2-carboxamide.

Pharmaceutical Compositions

According to a further aspect of the invention there is provided a pharmaceutical composition which comprises a compound of the invention as defined hereinbefore, or a pharmaceutically acceptable salt, hydrate or solvate thereof, in association with a pharmaceutically acceptable diluent or carrier.

The compositions of the invention may be in a form suitable for oral use (for Example as tablets, lozenges, hard or soft capsules, aqueous or oily suspensions, emulsions, dispersible powders or granules, syrups or elixirs), for topical use (for Example as creams, ointments, gels, or aqueous or oily solutions or suspensions), for administration by inhalation (for Example as a finely divided powder or a liquid aerosol), for administration by insufflation (for Example as a finely divided powder) or for parenteral administration (for Example as a sterile aqueous or oily solution for intravenous, subcutaneous, intramuscular, intraperitoneal or intramuscular dosing or as a suppository for rectal dosing).

The compositions of the invention may be obtained by conventional procedures using conventional pharmaceutical excipients, well known in the art. Thus, compositions intended for oral use may contain, for Example, one or more colouring, sweetening, flavouring and/or preservative agents.

An effective amount of a compound of the present invention for use in therapy is an amount sufficient to treat or prevent a proliferative condition referred to herein, slow its progression and/or reduce the symptoms associated with the condition.

The amount of active ingredient that is combined with one or more excipients to produce a single dosage form will necessarily vary depending upon the individual treated and the particular route of administration. For Example, a formulation intended for oral administration to humans will generally contain, for Example, from 0.5 mg to 0.5 g of active agent (more suitably from 0.5 to 100 mg, for Example from 1 to 30 mg) compounded with an appropriate and convenient amount of excipients which may vary from about 5 to about 98 percent by weight of the total composition.

The size of the dose for therapeutic or prophylactic purposes of a compound of the formula I will naturally vary according to the nature and severity of the conditions, the age and sex of the animal or patient and the route of administration, according to well-known principles of medicine.

In using a compound of the invention for therapeutic or prophylactic purposes it will generally be administered so that a daily dose in the range, for Example, 0.1 mg/kg to 75 mg/kg body weight is received, given if required in divided doses. In general lower doses will be administered when a parenteral route is employed. Thus, for Example, for intravenous or intraperitoneal administration, a dose in the range, for Example, 0.1 mg/kg to 30 mg/kg body weight will generally be used. Similarly, for administration by inhalation, a dose in the range, for Example, 0.05 mg/kg to 25 mg/kg body weight will be used. Oral administration may also be suitable, particularly in tablet form. Typically, unit dosage forms will contain about 0.5 mg to 0.5 g of a compound of this invention.

Therapeutic Uses and Applications

The present invention provides compounds that function as inhibitors of RET. Furthermore, the compounds of the present invention demonstrate an improved selectivity for RET relative to KDR (i.e. they are potent inhibitors of RET and poor inhibitors of KDR).

The present invention therefore provides a method of inhibiting RET kinase enzyme activity in vitro or in vivo, said method comprising contacting a cell with an effective amount of a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein.

The present invention also provides a method of selectively inhibiting RET kinase enzyme activity over KDR enzyme activity in vitro or in vivo, said method comprising contacting a cell with an effective amount of a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein.

The present invention also provides a method of treating a disease or disorder in which RET kinase activity is implicated in a patient in need of such treatment, said method comprising administering to said patient a therapeutically effective amount of a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, or a pharmaceutical composition as defined herein.

The present invention provides a method of inhibiting cell proliferation, in vitro or in vivo, said method comprising contacting a cell with an effective amount of a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein.

The present invention provides a method of treating a proliferative disorder in a patient in need of such treatment, said method comprising administering to said patient a therapeutically effective amount of a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, or a pharmaceutical composition as defined herein.

The present invention provides a method of treating cancer in a patient in need of such treatment, said method comprising administering to said patient a therapeutically effective amount of a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, or a pharmaceutical composition as defined herein.

The present invention provides a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, or a pharmaceutical composition as defined herein for use in therapy.

The present invention provides a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, or a pharmaceutical composition as defined herein for use in the treatment of a proliferative condition.

The present invention provides a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, or a pharmaceutical composition as defined herein for use in the treatment of cancer. In a particular embodiment, the cancer is human cancer.

The present invention provides a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein for use in the inhibition of RET kinase enzyme activity.

The present invention provides a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein for use in the selective inhibition of RET kinase enzyme activity over KDR enzyme activity.

The present invention provides a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein for use in the treatment of a disease or disorder in which RET kinase activity is implicated.

The present invention provides a use of a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein in the manufacture of a medicament for the treatment of a proliferative condition.

The present invention provides a use of a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein in the manufacture of a medicament for the treatment of cancer. Suitably, the medicament is for use in the treatment of human cancers.

The present invention provides a use of a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein in the manufacture of a medicament for the inhibition of RET kinase enzyme activity.

The present invention provides a use of a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein in the manufacture of a medicament for the selective inhibition of RET kinase enzyme activity over KDR enzyme activity.

The present invention provides a use of a compound, or a pharmaceutically acceptable salt, hydrate or solvate thereof, as defined herein in the manufacture of a medicament for the treatment of a disease or disorder in which RET kinase activity is implicated.

The term “proliferative disorder” are used interchangeably herein and pertain to an unwanted or uncontrolled cellular proliferation of excessive or abnormal cells which is undesired, such as, neoplastic or hyperplastic growth, whether in vitro or in vivo. Examples of proliferative conditions include, but are not limited to, pre-malignant and malignant cellular proliferation, including but not limited to, malignant neoplasms and tumours, cancers, leukemias, psoriasis, bone diseases, fibroproliferative disorders (e.g., of connective tissues), and atherosclerosis. Any type of cell may be treated, including but not limited to, lung, colon, breast, ovarian, prostate, liver, pancreas, brain, and skin.

The anti-proliferative effects of the compounds of the present invention have particular application in the treatment of human cancers (by virtue of their inhibition of RET kinase enzyme activity, and/or the selective inhibition of RET kinase enzyme activity over KDR enzyme activity).

The anti-cancer effect may arise through one or more mechanisms, including but not limited to, the regulation of cell proliferation, the inhibition of angiogenesis (the formation of new blood vessels), the inhibition of metastasis (the spread of a tumour from its origin), the inhibition of invasion (the spread of tumour cells into neighbouring normal structures), or the promotion of apoptosis (programmed cell death).

In a particular embodiment of the invention, the proliferative condition to be treated is cancer, for Example medullary thyroid cancer (MTC) or non-small cell lung cancer (NSCLC).

Routes of Administration

The compounds of the invention or pharmaceutical compositions comprising these compounds may be administered to a subject by any convenient route of administration, whether systemically/peripherally or topically (i.e., at the site of desired action).

Routes of administration include, but are not limited to, oral (e.g, by ingestion); buccal; sublingual; transdermal (including, e.g., by a patch, plaster, etc.); transmucosal (including, e.g., by a patch, plaster, etc.); intranasal (e.g., by nasal spray); ocular (e.g., by eye drops); pulmonary (e.g., by inhalation or insufflation therapy using, e.g., via an aerosol, e.g., through the mouth or nose); rectal (e.g., by suppository or enema); vaginal (e.g., by pessary); parenteral, for Example, by injection, including subcutaneous, intradermal, intramuscular, intravenous, intra-arterial, intracardiac, intrathecal, intraspinal, intracapsular, subcapsular, intraorbital, intraperitoneal, intratracheal, subcuticular, intraarticular, subarachnoid, and intrasternal; by implant of a depot or reservoir, for Example, subcutaneously or intramuscularly.

Combination Therapies

The antiproliferative treatment defined hereinbefore may be applied as a sole therapy or may involve, in addition to the compound of the invention, conventional surgery or radiotherapy or chemotherapy. Such chemotherapy may include one or more of the following categories of anti-tumour agents:—

(i) other antiproliferative/antineoplastic drugs and combinations thereof, as used in medical oncology, such as alkylating agents (for Example cis-platin, oxaliplatin, carboplatin, cyclophosphamide, nitrogen mustard, melphalan, chlorambucil, busulphan, temozolamide and nitrosoureas); antimetabolites (for Example gemcitabine and antifolates such as fluoropyrimidines like 5-fluorouracil and tegafur, raltitrexed, methotrexate, cytosine arabinoside, and hydroxyurea); antitumour antibiotics (for Example anthracyclines like adriamycin, bleomycin, doxorubicin, daunomycin, epirubicin, idarubicin, mitomycin-C, dactinomycin and mithramycin); antimitotic agents (for Example vinca alkaloids like vincristine, vinblastine, vindesine and vinorelbine and taxoids like taxol and taxotere and polokinase inhibitors); and topoisomerase inhibitors (for Example epipodophyllotoxins like etoposide and teniposide, amsacrine, topotecan and camptothecin); (ii) cytostatic agents such as antioestrogens (for Example tamoxifen, fulvestrant, toremifene, raloxifene, droloxifene and iodoxyfene), antiandrogens (for Example bicalutamide, flutamide, nilutamide and cyproterone acetate), LHRH antagonists or LHRH agonists (for Example goserelin, leuprorelin and buserelin), progestogens (for Example megestrol acetate), aromatase inhibitors (for Example as anastrozole, letrozole, vorazole and exemestane) and inhibitors of 5α-reductase such as finasteride; (iii) anti-invasion agents [for Example c-Src kinase family inhibitors like 4-(6-chloro-2,3-methylenedioxyanilino)-7-[2-(4-methylpiperazin-1-yl)ethoxy]-5-tetrahydropyran-4-yloxyquinazoline (AZD0530; International Patent Application WO 01/94341), N-(2-chloro-6-methylphenyl)-2-{6-[4-(2-hydroxyethyl)piperazin-1-yl]-2-methylpyrimidin-4-ylamino}thiazole-5-carboxamide (dasatinib, BMS-354825; J. Med. Chem., 2004, 47, 6658-6661) and bosutinib (SKI-606), and metalloproteinase inhibitors like marimastat, inhibitors of urokinase plasminogen activator receptor function or antibodies to Heparanase]; (iv) inhibitors of growth factor function: for Example such inhibitors include growth factor antibodies and growth factor receptor antibodies (for Example the anti-erbB2 antibody trastuzumab [Herceptin™], the anti-EGFR antibody panitumumab, the anti-erbB1 antibody cetuximab [Erbitux, C225] and any growth factor or growth factor receptor antibodies disclosed by Stern et al. (Critical reviews in oncology/haematology, 2005, Vol. 54, pp 11-29); such inhibitors also include tyrosine kinase inhibitors, for Example inhibitors of the epidermal growth factor family (for Example EGFR family tyrosine kinase inhibitors such as N-(3-chloro-4-fluorophenyl)-7-methoxy-6-(3-morpholinopropoxy)quinazolin-4-amine (gefitinib, ZD1839), N-(3-ethynylphenyl)-6,7-bis(2-methoxyethoxy)quinazolin-4-amine (erlotinib, OSI-774) and 6-acrylamido-N-(3-chloro-4-fluorophenyl)-7-(3-morpholinopropoxy)-quinazolin-4-amine (CI 1033), erbB2 tyrosine kinase inhibitors such as lapatinib); inhibitors of the hepatocyte growth factor family; inhibitors of the insulin growth factor family; inhibitors of the platelet-derived growth factor family such as imatinib and/or nilotinib (AMN107); inhibitors of serine/threonine kinases (for Example Ras/Raf signalling inhibitors such as farnesyl transferase inhibitors, for Example sorafenib (BAY 43-9006), tipifarnib (R115777) and lonafarnib (SCH66336)), inhibitors of cell signalling through MEK and/or AKT kinases, c-kit inhibitors, abl kinase inhibitors, PI3 kinase inhibitors, Plt3 kinase inhibitors, CSF-1R kinase inhibitors, IGF receptor (insulin-like growth factor) kinase inhibitors; aurora kinase inhibitors (for Example AZD1152, PH739358, VX-680, MLN8054, R763, MP235, MP529, VX-528 AND AX39459) and cyclin dependent kinase inhibitors such as CDK2 and/or CDK4 inhibitors; (v) antiangiogenic agents such as those which inhibit the effects of vascular endothelial growth factor, [for Example the anti-vascular endothelial cell growth factor antibody bevacizumab (Avastin™) and for Example, a VEGF receptor tyrosine kinase inhibitor such as vandetanib (ZD6474), vatalanib (PTK787), sunitinib (SU11248), axitinib (AG-013736), pazopanib (GW 786034) and 4-(4-fluoro-2-methylindol-5-yloxy)-6-methoxy-7-(3-pyrrolidin-1-ylpropoxy)quinazoline (AZD2171; Example 240 within WO 00/47212), compounds such as those disclosed in International Patent Applications WO97/22596, WO 97/30035, WO 97/32856 and WO 98/13354 and compounds that work by other mechanisms (for Example linomide, inhibitors of integrin αvβ function and angiostatin)]; (vi) vascular damaging agents such as Combretastatin A4 and compounds disclosed in International Patent Applications WO 99/02166, WO 00/40529, WO 00/41669, WO 01/92224, WO 02/04434 and WO 02/08213; (vii) an endothelin receptor antagonist, for Example zibotentan (ZD4054) or atrasentan; (viii) antisense therapies, for Example those which are directed to the targets listed above, such as ISIS 2503, an anti-ras antisense; (ix) gene therapy approaches, including for Example approaches to replace aberrant genes such as aberrant p53 or aberrant BRCA1 or BRCA2, GDEPT (gene-directed enzyme pro-drug therapy) approaches such as those using cytosine deaminase, thymidine kinase or a bacterial nitroreductase enzyme and approaches to increase patient tolerance to chemotherapy or radiotherapy such as multi-drug resistance gene therapy; and (x) immunotherapy approaches, including for Example ex-vivo and in-vivo approaches to increase the immunogenicity of patient tumour cells, such as transfection with cytokines such as interleukin 2, interleukin 4 or granulocyte-macrophage colony stimulating factor, approaches to decrease T-cell anergy, approaches using transfected immune cells such as cytokine-transfected dendritic cells, approaches using cytokine-transfected tumour cell lines and approaches using anti-idiotypic antibodies.

In a particular embodiment, the antiproliferative treatment defined hereinbefore may involve, in addition to the compound of the invention, conventional surgery or radiotherapy or chemotherapy, wherein the chemotherapy may include one or more anti-tumour agents selected from procarbazine, carmustine, lomustine, irinotecan, temozolomide, cisplatin, carboplatin, methotrexate, etoposide, cyclophosphamide, ifosfamide, and vincristine.

Such conjoint treatment may be achieved by way of the simultaneous, sequential or separate dosing of the individual components of the treatment. Such combination products employ the compounds of this invention within the dosage range described hereinbefore and the other pharmaceutically-active agent within its approved dosage range.

According to this aspect of the invention there is provided a combination for use in the treatment of a cancer (for Example a cancer involving a solid tumour) comprising a compound of the invention as defined hereinbefore, or a pharmaceutically acceptable salt, hydrate or solvate thereof, and another anti-tumour agent.

According to this aspect of the invention there is provided a combination for use in the treatment of a proliferative condition, such as cancer (for Example a cancer involving a solid tumour), comprising a compound of the invention as defined hereinbefore, or a pharmaceutically acceptable salt, hydrate or solvate thereof, and any one of the anti-tumour agents listed herein above.

In a further aspect of the invention there is provided a compound of the invention or a pharmaceutically acceptable salt, hydrate or solvate thereof, for use in the treatment of cancer in combination with another anti-tumour agent, optionally selected from one listed herein above.

Herein, where the term “combination” is used it is to be understood that this refers to simultaneous, separate or sequential administration. In one aspect of the invention “combination” refers to simultaneous administration. In another aspect of the invention “combination” refers to separate administration. In a further aspect of the invention “combination” refers to sequential administration. Where the administration is sequential or separate, the delay in administering the second component should not be such as to lose the beneficial effect of the combination.

According to a further aspect of the invention there is provided a pharmaceutical composition which comprises a compound of the invention, or a pharmaceutically acceptable salt, hydrate or solvate thereof, in combination with an anti-tumour agent (optionally selected from one listed herein above), in association with a pharmaceutically acceptable diluent or carrier.

EXAMPLES Abbreviations

-   B₂(OH)₄ Tetrahydroxyborate -   br s broad singlet -   d doublet -   dd doublet of doublets -   CDCl₃ Chloroform -   DMAP 4-(dimethylamino) pyridine -   DCM Dichloromethane (methylene chloride) -   DIPEA N,N,-di-isopropyethylamine, Hunig's base -   DMF N,N-dimethylformamide -   DMSO Dimethylsulfoxide. -   EDCI.HCl 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride -   EtBr Ethylbromide (bromoethane) -   EtOAc Ethyl acetate -   EtOH Ethanol (ethyl alcohol) -   HATU     1-[Bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium     3-oxid hexafluorophosphate) -   HCl Hydrochloric acid -   HPLC High Pressure Liquid Chromatography -   Hz Hertz -   J Coupling constant -   K₂CO₃ Potassium carbonate -   KOAc Potassium acetate -   LCMS Liquid Chromatography-Mass Spectrometry -   LiOH.H₂O Lithium hydroxide monohydrate -   m multiplet -   MeOH Methanol (methyl alcohol) -   MgSO₄ Magnesium sulphate -   MHz Mega hertz -   N₂ Nitrogen -   NaHCO₃ Sodium Bicarbonate -   Na₂SO₄ Sodium sulphate -   NH₄Cl Ammonium chloride -   NMR Nuclear Magnetic Resonance -   POCl₃ Phosphorus oxychloride -   q quartet -   s singlet -   t triplet -   tt triplet of triplets -   THF Tetrahydrofuran -   XPhos 2-Dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl -   XPhos-Pd-G2     Chloro(2-dicyclohexylphosphino-2′,4′,6′-triisopropyl-1,1′-biphenyl)[2-(2′-amino-1,1′-biphenyl)]palladium(II)

Methods General Experimental

Flash chromatography was performed using pre-packed silica gel cartridges. Thin layer chromatography was conducted with 5×10 cm plates coated with Merck Type 60 F₂₅₄ silica gel to a thickness of 0.25 mm. All reagents obtained from commercial sources were used without further purification. Anhydrous solvents were obtained from the Sigma-Aldrich Chemical Company Ltd. or Fisher Chemicals Ltd., and used without further drying. HPLC grade solvents were obtained from Fisher Chemicals Ltd.

All compounds were >90% purity as determined by examination of both the LC-MS and ¹H NMR spectra unless otherwise indicated. Where Cl or Br were present, expected isotopic distribution patterns were observed.

NMR

Proton (¹H) NMR spectra were recorded on a 300 MHz or 400 MHz Bruker spectrometer. Solutions were typically prepared in either deuterochloroform (CDCl₃) or deuterated dimethylsulfoxide (DMSO-d₆) with chemical shifts referenced to tetramethylsilane (TMS) or deuterated solvent as an internal standard. ¹H NMR data are reported indicating the chemical shift (5), the integration (e.g. ¹H), the multiplicity (s, singlet; d, doublet; t, triplet; q, quartet; m, multiplet; br, broad; dd, doublet of doublets etc.) and the coupling constant (J) in Hz (app implies apparent coupling on broadened signals). Deuterated solvents were obtained from the Sigma-Aldrich Chemical Company, Goss or Fluorochem.

LCMS Methods Analytical LC-MS.

LC-MS analyses were performed on a Waters Acquity UPLC system fitted with BEH C18 1.7 μM columns (2.1×50 mm or 2.1×100 mm) and with UV diode array detection (210-400 nm). Positive and negative mass ion detection was performed using a Waters SQD detector. Analyses were performed with either buffered acidic or basic solvents and gradients as detailed below:

Low pH:

Solvent A—Water+10 mM ammonium formate+0.1% formic acid Solvent B—Acetonitrile+5% water+0.1% formic acid

High pH:

Solvent A—Water+10 mM ammonium hydrogen carbonate+0.1% ammonia solution Solvent B—Acetonitrile+0.1% ammonia solution

Gradient: Flow rate Time (mL/min) % Solvent A % Solvent B 0 0.6 95 5 1.2 0.6 5 95 1.7 0.6 5 95 1.8 0.6 95 5

Preparative HPLC

Some compounds were purified by preparative HPLC on a Waters FractionLynx MS autopurification system, with a Waters XBridge 5 μm C18, 100 mm×19 mm i.d. column, running at a flow rate of 20 mL/min with UV diode array detection (210-400 nm) and mass-directed collection using both positive and negative mass ion detection.

Purifications were performed using buffered acidic or basic solvent systems as appropriate. Compound retention times on the system were routinely assessed using a 30-50 μL test injection and a standard gradient, and then purified using an appropriately chosen focused gradient as detailed below, based upon observed retention time.

Low pH:

Solvent A—Water+10 mM ammonium formate+0.1% formic acid Solvent B—Acetonitrile+5% water+0.1% formic acid

High pH:

Solvent A—Water+10 mM ammonium formate+0.1% ammonia solution Solvent B—Acetonitrile+5% water+0.1% ammonia solution

Standard Gradient: Flow rate Time (mL/min) % Solvent A % Solvent B 0 20 90 10 0.3 20 90 10 8.5 20 2 98 12 20 2 98 12.5 0 2 98

Focussed Gradients: % Solvent B Flow rate Retention time on standard gradient (min.) Time (mL/min) 0-5.2 4.9-6.6 6.3-7.5 7.3-9.5 9.3-12 0 20 10 10 10 10 10 0.25 20 10 10 10 10 10 0.35 20 10 20 35 45 60 10 20 45 55 65 75 98 12 20 98 98 98 98 98 12.5 0 98 98 98 98 98

Synthetic Methods

Several methods for the chemical synthesis of the compounds of the present invention are described herein. These and/or other well-known methods may be modified and/or adapted in known ways in order to facilitate the synthesis of additional compounds within the scope of the present invention.

Intermediates 6-(4-Amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic Acid

A mixture of 6-chloro-1H-indole-2-carboxylic acid (1.92 g, 9.8 mmol), XPhos-Pd-G2 (155 mg, 0.2 mmol), XPhos (187 mg, 0.4 mmol), B₂(OH)₄ (2.59 g, 29.5 mmol) and KOAc (2.89 g, 29.5 mmol) in EtOH (80 ml) was heated at 80° C. for 2 hours under N₂. A solution of K₂CO₃ (4.07 g, 29.8 mmol) in water (20 ml) and a solution of 3-bromo-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine (1.96 g, 7.3 mmol) in 1,4-dioxane (25 ml) were added and the mixture heated at 80° C. for 15 hours. The reaction was cooled to room temperature, concentrated under reduced pressure to remove organics, then acidified to pH5 with 1M aq HCl to return a solid which was collected by filtration, washed with water and dried under vacuum at 50° C. to return 6-(4-amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid (2.92 g, 85%) as an off-white solid.

LCMS: [M+H]⁺ 351.2

¹H NMR: (300 MHz, DMSO-d₆) δ 11.91 (s, 1H), 8.25 (s, 1H), 7.80 (d, J=8.29 Hz, 1H), 7.71 (s, 1H), 7.37 (dd, J=1.32, 8.10 Hz, 1H), 7.17 (d, J=1.51 Hz, 1H), 6.51 (s, 2H), 1.77 (s, 9H).

6-(4-Amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-3-chloro-1H-indole-2-carboxylic Acid

To a solution of 6-(4-amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid (793 mg, 2.3 mmol) in DMF (10 mL) was added N-chlorosuccinimide (302.23 mg, 2.3 mmol) at room temperature. The reaction was stirred for 18 hours before diluting with water (50 ml). The resultant suspension was stirred for 10 min, filtered, washed with water and dried in vacuo to return 6-(4-amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-3-chloro-1H-indole-2-carboxylic acid (518 mg, 1.3 mmol, 60%) as a purple solid. The material was used without further purification.

LCMS: Purity 58%, [M−H]− 383.2.

¹H NMR (300 MHz, DMSO-d6) δ 12.18 (s, 1H), 8.27 (s, 1H), 7.69-7.80 (m, 2H), 7.48 (dd, J=1.41, 8.38 Hz, 1H), 1.77 (s, 9H).

6-(4-Amino-1-isopropyl-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic Acid

Prepared as described for 6-(4-amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid using 3-bromo-1-isopropyl-1H-pyrazolo[3,4-d]pyrimidin-4-amine in place of 3-bromo-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine to return (2.88 g, 86%) as an off-white solid.

LCMS: [M+H]⁺ 337.2.

6-Bromo-N-methyl-1H-indole-2-carboxamide

To a solution of 6-bromo-1H-indole-2-carboxylic acid (1.0 g, 4.2 mmol) in DMF (25 ml) was added DIPEA (1.7 ml, 10.0 mmol), methylamine hydrochloride (338 mg, 5.0 mmol) and HATU 1.9 g, 5.0 mmol). The mixture was stirred at room temperature for 18 hours then partitioned between water and EtOAc. The organic layer was separated and washed with sat. aq. NaHCO₃ and brine, dried over Na₂SO₄, filtered and concentrated under reduced pressure. The residue was purified by flash column chromatography (40 g column, 0-100% EtOAc in isohexane) to return 6-bromo-N-methyl-1H-indole-2-carboxamide (657 mg, 63%) as a tan solid.

LCMS: [M+H]⁺ 253.0/254.9

¹H NMR: (400 MHz, DMSO-d₆) δ 11.71 (br s, 1H), 8.52 (q, J=4.09 Hz, 1H), 7.59 (d, J=6.55 Hz, 2H), 7.58 (s, 1H), 7.13-7.18 (m, 1H), 7.08 (s, 1H), 2.81 (d, J=4.64 Hz, 3H).

6-Bromo-N-cyclopropyl-1H-indole-2-carboxamide

Prepared as described for 6-bromo-N-methyl-1H-indole-2-carboxamide using cyclopropylamine in place of methylamine hydrochloride to return (181 mg, 62%) as a white solid.

LCMS: [M+H]⁺ 278.9/280.9.

6-Bromo-N-ethyl-1H-indole-2-carboxamide

Prepared as described for 6-bromo-N-methyl-1H-indole-2-carboxamide using ethylamine in place of methylamine hydrochloride to return (144 mg, 52%) as a white solid.

LCMS: [M+H]⁺ 266.9/268.9.

¹H NMR: (400 MHz, CHLOROFORM-d) δ 9.51 (br s, 1H), 7.61 (s, 1H), 7.50 (d, J=8.54 Hz, 1H), 7.24 (dd, J=1.71, 8.54 Hz, 1H), 6.77 (dd, J=0.70, 2.04 Hz, 1H), 6.13 (br s, 1H), 3.55 (dq, J=5.89, 7.23 Hz, 2H), 1.30 (t, J=7.29 Hz, 3H).

6-Bromo-N-cyclobutyl-1H-indole-2-carboxamide

Prepared as described for 6-bromo-N-methyl-1H-indole-2-carboxamide using cyclobutylamine in place of methylamine hydrochloride to return (268 mg, 73%) as a beige solid.

LCMS: [M+H]+ 293.1/295.1.

¹H NMR (400 MHz, DMSO-d₆) δ 11.66 (s, 1H), 8.67 (d, J=7.75 Hz, 1H), 7.58 (s, 1H), 7.59 (d, J=8.94 Hz, 1H), 7.11-7.19 (m, 2H), 4.44 (sxt, J=8.17 Hz, 1H), 2.17-2.30 (m, 2H), 2.01-2.14 (m, 2H), 1.60-1.77 (m, 2H).

6-Bromo-N-methoxy-1H-indole-2-carboxamide

Prepared as described for 6-bromo-N-methyl-1H-indole-2-carboxamide using O-methylhydroxylamine hydrochloride in place of methylamine hydrochloride to return (300 mg, 89%) as an off-white solid.

LCMS: [M+H]⁺ 269.0/271.0.

6-Bromo-3-fluoro-N-methyl-1H-indole-2-carboxamide

Step 1: To a suspension of ethyl 6-bromo-1H-indole-2-carboxylate (688 mg, 2.6 mmol) in acetonitrile (30 mL) was added saturated aq. NaHCO₃ (5.6 ml). The mixture was ice-cooled before portionwise addition of Selectfluor™ (1 g, 2.8 mmol). The solution was warmed to room temperature and then heated at 80° C. for 4 hours. The solution was cooled to room temperature before adding a further charge of Selectfluor (1 g, 2.8 mmol) and heating at 80° C. for 1 hour. The mixture was cooled to room temperature and diluted with water then extracted with ethyl acetate (×3). The combined organic phases were dried over Na₂SO₄ and concentrated under reduced pressure. The residue was purified by flash column chromatography (0-50% ethyl acetate in cyclohexane) to return ethyl 6-bromo-3-fluoro-1H-indole-2-carboxylate (362 mg) as a pale yellow solid. The product was not pure but was used in the next step.

Step 2: To a solution of ethyl 6-bromo-3-fluoro-1H-indole-2-carboxylate (362 mg) in THF (10 mL) was added a solution of LiOH.H₂O (213 mg, 5.1 mmol) in water (6.4 mL). The mixture was stirred at room temperature for 3 hours. A further charge of LiOH.H₂O (213 mg, 5.1 mmol) in water (6.4 mL) was added and the mixture was heated at 60° C. for 2 hours. The mixture was cooled to room temperature and then concentrated under reduced pressure. The residue was acidified with 1M aq. HCl and extracted with EtOAc (×3). The combined organic phases were dried over Na₂SO₄ and evaporated under reduced pressure to give 6-bromo-3-fluoro-1H-indole-2-carboxylic acid (322 mg) as a pale yellow solid. The impure product was used without further purification.

Step 3: The impure acid (322 mg) was subjected to amide coupling conditions as described for 6-bromo-N-methyl-1H-indole-2-carboxamide to return 6-bromo-3-fluoro-N-methyl-1H-indole-2-carboxamide (52 mg, 7% over 3 steps) as a pale yellow solid. The material was progressed although not pure.

6-Bromo-N,3-dimethyl-1H-indole-2-carboxamide

Step 1: To a solution of 6-bromo-N-methyl-1H-indole-2-carboxamide (2.3 g, 9.1 mmol) in DMF (10 mL) at 0° C. was added POCl₃ (1.67 g, 10.9 mmol). The mixture was stirred at room temperature for 15 mins then at 100° C. for 5 h. The mixture was poured into ice water (100 mL) and the product was extracted with EtOAc (4×100 mL). The combined organic phases were washed with brine (100 mL), dried over MgSO₄ and concentrated under reduced pressure. The residue was purified by flash column chromatography to return 6-bromo-3-formyl-N-methyl-1H-indole-2-carboxamide (2.1 g). The material was impure but was progressed into the next stage.

Step 2: To a solution of 6-bromo-3-formyl-N-methyl-1H-indole-2-carboxamide (2.1 g) in trifluoroacetic acid (15 mL) at 0° C. was added triethylsilane (608 mg, 5.2 mmol). The mixture was stirred at room temperature for 18 hours and then poured into saturated aq. Na₂CO₃ (100 ml) and extracted with EtOAc (5×100 ml). The combined organic phases were washed with brine (100 mL), dried over MgSO₄ and concentrated under reduced pressure. The residue was purified by flash column chromatography to obtain 6-bromo-N,3-dimethyl-1H-indole-2-carboxamide (388 mg, 16% over 2 steps). The material was progressed although not pure.

6-Bromo-N-(1,3-dimethyl-1H-pyrazol-5-yl)-1H-indole-2-carboxamide

To a solution of 1,3-dimethyl-1H-pyrazol-5-amine (86 mg, 0.8 mmol) in pyridine (5 ml) was added 6-bromo-1H-indole-2-carbonyl chloride (200 mg, 0.8 mmol). The mixture was stirred at room temperature for 2 hours then concentrated under reduced pressure. The residue was diluted with sat aq NaHCO₃ then extracted with EtOAc (3×20 ml). The combined organic phases were concentrated under reduced pressure. The residue was purified by flash column chromatography (1:1 EtOAc:petroleum ether) to return 6-bromo-N-(1,3-dimethyl-1H-pyrazol-5-yl)-1H-indole-2-carboxamide (50 mg, 19%).

LCMS: [M+H]⁺ 333.0/335.0.

3-Bromo-1-ethyl-1H-pyrazolo[3,4-d]pyrimidin-4-amine

A mixture of 3-bromo-1H-pyrazolo[3,4-d]pyrimidin-4-amine (1 g, 4.7 mmol) and K₂CO₃ (1.29 g, 9.3 mmol) in DMF (10 mL) was heated at 60° C. under nitrogen for 30 min. The solution was cooled to room temperature before adding EtBr (0.42 mL, 5.6 mmol). The mixture was heated at 60° C. under nitrogen for 4 h then cooled to room temperature and concentrated under reduced pressure. The residue was partitioned between water and EtOAc. The organic layer was dried over MgSO₄, filtered and concentrated under reduced pressure to obtain the crude product (980 mg, 87%) as a yellow solid, which was used directly for the next reaction without further purification.

LCMS: [M+H]⁺ 242.0/244.0.

3-Bromo-1-cyclopropyl-1H-pyrazolo[3,4-d]pyrimidin-4-amine

To a solution 3-bromo-1H-pyrazolo[3,4-d]pyrimidin-4-amine (1.2 g, 5 mmol) in 1,2-dichloroethane (50 mL), cyclopropylboronic acid (860 mg, 10 mmol), copper (II) acetate (908 mg, 5 mmol), 2,2′-bipyridine (780 mg, 5 mmol) and NaHCO₃ (1.1 g, 10 mmol) were added. The mixture was stirred at 70° C. under air for 2 h and then cooled to room temperature. The reaction mixture was quenched with sat. aq. NH₄Cl (100 mL) and extracted with dichloromethane (3×50 mL). The combined organic phases were washed with brine, dried over Na₂SO₄, filtered and concentrated under reduced pressure. The residue was purified by flash chromatography (0-100% EtOAc in isohexane) to return 3-bromo-1-cyclopropyl-1H-pyrazolo[3,4-d]pyrimidin-4-amine (121 mg, 9%) as a white solid.

LCMS: [M+H]⁺ 254.0/256.0.

¹H NMR (400 MHz, CHLOROFORM-d) δ 8.38 (s, 1H), 5.89 (br s, 2H), 3.73 (tt, J=3.71, 7.28 Hz, 1H), 1.27-1.34 (m, 2H), 1.12-1.19 (m, 2H).

Final Compounds Example 1—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-thiazol-2-yl-1H-indole-2-carboxamide

To a mixture of 6-(4-amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid (50 mg, 0.14 mmol) and HATU (65 mg, 0.17 mmol) in DMF (1 ml) was added DIPEA (0.07 ml, 0.42 mmol). The mixture was stirred for 5 mins before adding 2-aminothiazole (17 mg, 0.17 mmol). The mixture was stirred at room temperature for 18 hours then diluted with water and extracted with EtOAc (3×). The combined extracts were dried over Na₂SO₄, filtered and concentrated under reduced pressure. The residue was purified by preparative HPLC to return 6-(4-amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-thiazol-2-yl-1H-indole-2-carboxamide (14 mg, 0.03 mmol, 23%) as a yellow solid.

LCMS: Purity>95%, [M+H]⁺ 433.1.

¹H NMR (400 MHz, DMSO-d6) δ 12.04 (br s, 1H), 8.36 (s, 1H), 8.25 (s, 1H), 7.84 (d, J=7.89 Hz, 1H), 7.75 (s, 1H), 7.71 (s, 1H), 7.57 (d, J=3.55 Hz, 1H), 7.39 (dd, J=1.47, 8.25 Hz, 1H), 7.27 (d, J=3.61 Hz, 1H), 1.78 (s, 9H).

Example 2—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-butyl-1H-indole-2-carboxamide

Prepared as described for Example 1 using n-butylamine in place of 2-aminothiazole to return (26 mg, 51%) as a white solid.

LCMS: Purity>95%, [M+H]⁺ 406.2.

¹H NMR (400 MHz, DMSO-d6) δ 11.66-11.76 (m, 1H), 8.50 (t, J=5.72 Hz, 1H), 8.24 (s, 1H), 7.77 (d, J=8.25 Hz, 1H), 7.69 (s, 1H), 7.33 (dd, J=1.47, 8.25 Hz, 1H), 7.19 (d, J=1.28 Hz, 1H), 3.30 (br s, 2H), 1.77 (s, 9H), 1.54 (quin, J=7.20 Hz, 2H), 1.36 (sxt, J=7.70 Hz, 2H), 0.93 (t, J=7.34 Hz, 3H).

Example 3—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2-methoxyethyl)-1H-indole-2-carboxamide

Prepared as described for Example 1 using 2-methoxyethylamine in place of 2-aminothiazole to return (30 mg, 53%) as a white solid.

LCMS: Purity>95%, [M+H]⁺ 408.2.

¹H NMR (400 MHz, DMSO-d6) δ 11.65-11.82 (m, 1H), 8.53-8.66 (m, 1H), 8.24 (s, 1H), 7.77 (d, J=8.25 Hz, 1H), 7.70 (s, 1H), 7.34 (dd, J=1.47, 8.25 Hz, 1H), 7.21 (d, J=1.34 Hz, 1H), 3.43-3.55 (m, 5H), 3.30 (s, 2H), 1.77 (s, 9H).

Example 4—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-propyl-1H-indole-2-carboxamide

Prepared as described for Example 1 using n-propylamine in place of 2-aminothiazole to return (33 mg, 60%) as a white solid.

LCMS: Purity>95%, [M+H]+ 392.2.

¹H NMR (400 MHz, DMSO-d₆) δ 11.70-11.74 (m, 1H), 8.53 (t, J=5.72 Hz, 1H), 8.24 (s, 1H), 7.77 (d, J=8.25 Hz, 1H), 7.69 (s, 1H), 7.33 (dd, J=1.50, 8.22 Hz, 1H), 7.19 (s, 1H), 3.24-3.27 (m, 2H), 1.77 (s, 9H), 1.57 (sxt, J=7.34 Hz, 2H), 0.92 (t, J=7.40 Hz, 3H)

Example 5—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-methoxy-1H-indole-2-carboxamide

Prepared as described for Example 1 using O-methylhydroxylamine hydrochloride in place of 2-aminothiazole to return (51 mg, 47%) as a white solid.

LCMS: Purity>95%, [M+H]⁺ 380.2.

¹H NMR (400 MHz, DMSO-d6) δ 11.84 (br s, 1H), 8.24 (s, 1H), 7.77 (d, J=8.25 Hz, 1H), 7.70 (s, 1H), 7.34 (dd, J=1.44, 8.22 Hz, 1H), 7.06 (s, 1H), 3.76 (s, 3H), 1.77 (s, 9H)

Example 6—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2-fluoroethyl)-1H-indole-2-carboxamide

Prepared as described for Example 1 using 2-fluoroethylamine hydrochloride in place of 2-aminothiazole to return (32 mg, 28%) as a white solid.

LCMS: Purity>95%, [M+H]⁺ 396.3.

¹H NMR (300 MHz, DMSO-d₆) δ 11.80 (br s, 1H), 8.82 (br t, J=5.04 Hz, 1H), 8.25 (s, 1H), 7.79 (br d, J=8.19 Hz, 1H), 7.71 (s, 1H), 7.35 (br d, J=8.01 Hz, 1H), 7.25 (s, 1H), 4.66 (br t, J=4.76 Hz, 1H), 4.50 (br t, J=4.66 Hz, 1H), 3.66 (br d, J=4.80 Hz, 1H), 3.57 (br d, J=4.80 Hz, 1H), 1.77 (s, 9H)

Example 7—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-isobutyl-1H-indole-2-carboxamide

Prepared as described for Example 1 using isobutylamine in place of 2-aminothiazole to return (51 mg, 43%) as a white solid.

LCMS: Purity>95%, [M+H]⁺ 406.3.

¹H NMR (400 MHz, DMSO-d₆) δ 11.72-11.82 (m, 1H), 8.56 (t, J=5.93 Hz, 1H), 8.31 (s, 1H), 7.79 (d, J=8.25 Hz, 1H), 7.69 (s, 1H), 7.34 (dd, J=1.53, 8.25 Hz, 1H), 7.23 (d, J=1.34 Hz, 1H), 3.13 (t, J=6.67 Hz, 2H), 1.87 (spt, J=7.09 Hz, 1H), 1.77 (s, 9H), 0.92 (d, J=6.66 Hz, 6H)

Example 8—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-benzyl-1H-indole-2-carboxamide

Prepared as described for Example 1 using benzylamine in place of 2-aminothiazole to return (34 mg, 32%) as a white solid.

LCMS: Purity>95%, [M+H]⁺ 440.3.

¹H NMR (400 MHz, DMSO-d₆) δ 11.75-11.85 (m, 1H), 9.13 (t, J=6.08 Hz, 1H), 8.25 (s, 1H), 7.79 (d, J=8.25 Hz, 1H), 7.70 (s, 1H), 7.24-7.38 (m, 7H), 4.54 (d, J=6.05 Hz, 2H), 1.77 (s, 9H)

Example 9—6-(4-Amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-N-phenethyl-1H-indole-2-carboxamide

Prepared as described for Example 1 using phenethylamine in place of 2-aminothiazole to return (39 mg, 36%) as a white solid.

LCMS: Purity>95%, [M+H]+ 454.3.

¹H NMR (400 MHz, DMSO-d₆) δ 11.72-11.81 (m, 1H), 8.68 (t, J=5.69 Hz, 1H), 8.32 (s, 1H), 7.79 (d, J=8.31 Hz, 1H), 7.69 (s, 1H), 7.25-7.36 (m, 5H), 7.17-7.25 (m, 2H), 3.49-3.57 (m, 2H), 2.89 (t, J=7.37 Hz, 2H), 1.77 (s, 9H)

Example 10—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(cyclopropylmethyl)-1H-indole-2-carboxamide

Prepared as described for Example 1 using cyclopropylmethanamine in place of 2-aminothiazole to return (64 mg, 55%) as a beige solid.

LCMS: Purity>95%, [M+H]+ 404.2.

¹H NMR (400 MHz, DMSO-d₆) δ 11.73 (s, 1H), 8.63 (t, J=5.78 Hz, 1H), 8.24 (s, 1H), 7.78 (d, J=8.25 Hz, 1H), 7.70 (s, 1H), 7.34 (dd, J=1.47, 8.25 Hz, 1H), 7.22 (d, J=1.22 Hz, 1H), 3.19 (t, J=6.27 Hz, 2H), 1.77 (s, 9H), 1.06 (s, 1H), 0.43-0.50 (m, 2H), 0.23-0.30 (m, 2H)

Example 11—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2,2,2-trifluoroethyl)-1H-indole-2-carboxamide

Prepared as described for Example 1 using 2,2,2-trifluoroethan-1-amine in place of 2-aminothiazole to return (68 mg, 54%) as a beige solid.

LCMS: Purity>95%, [M+H]+ 432.2.

¹H NMR (400 MHz, DMSO-d₆) δ 11.85-11.95 (m, 1H), 9.17 (t, J=6.39 Hz, 1H), 8.32 (s, 1H), 7.82 (d, J=8.31 Hz, 1H), 7.71 (s, 1H), 7.37 (dt, J=1.59, 8.00 Hz, 1H), 7.33-7.35 (m, 1H), 4.09-4.20 (m, 2H), 1.78 (s, 9H).

Example 12—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2,2-difluoroethyl)-1H-indole-2-carboxamide

Prepared as described for Example 1 using 2,2-difluoroethan-1-amine in place of 2-aminothiazole to return (41 mg, 34%) as a yellow solid.

LCMS: Purity>95%, [M+H]+ 414.2.

¹H NMR (400 MHz, DMSO-d₆) δ 11.77-11.88 (m, 1H), 8.93 (t, J=5.99 Hz, 1H), 8.25 (s, 1H), 7.80 (d, J=8.25 Hz, 1H), 7.71 (s, 1H), 7.36 (dd, J=1.47, 8.25 Hz, 1H), 7.28 (d, J=1.34 Hz, 1H), 6.16 (tt, J=3.91, 55.80 Hz, 1H), 3.63-3.93 (m, 2H), 1.77 (s, 9H).

Example 13—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-ethoxy-1H-indole-2-carboxamide

Prepared as described for Example 1 using O-ethylhydroxylamine hydrochloride in place of 2-aminothiazole to return (56 mg, 49%) as a yellow solid.

LCMS: Purity>95%, [M+H]+ 394.2.

¹H NMR (400 MHz, DMSO-d6) δ 11.85 (br s, 1H), 11.75 (br s, 1H), 8.24 (s, 1H), 7.78 (d, J=8.25 Hz, 1H), 7.70 (s, 1H), 7.35 (dd, J=1.47, 8.25 Hz, 1H), 7.10 (s, 1H), 3.98 (q, J=7.00 Hz, 2H), 1.77 (s, 9H), 1.25 (t, J=7.00 Hz, 3H).

Example 14—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(cyclopropylmethoxy)-1H-indole-2-carboxamide

Prepared as described for Example 1 using O-(cyclopropylmethyl)hydroxylamine hydrochloride in place of 2-aminothiazole to return (68 mg, 56%) as a yellow solid.

LCMS: Purity>95%, [M+H]+ 420.2.

¹H NMR (400 MHz, DMSO-d6) δ 11.84 (s, 1H), 11.77 (br s, 1H), 8.28 (s, 1H), 7.78 (d, J=8.25 Hz, 1H), 7.70 (s, 1H), 7.35 (dd, J=1.44, 8.28 Hz, 1H), 7.10 (s, 1H), 3.76 (d, J=7.15 Hz, 2H), 1.77 (s, 9H), 1.14 (ddd, J=2.90, 4.65, 7.79 Hz, 1H), 0.52-0.60 (m, 2H), 0.25-0.34 (m, 2H).

Example 15—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(1,3,4-thiadiazol-2-yl)-1H-indole-2-carboxamide

Prepared as described for Example 1 using 1,3,4-thiadiazol-2-amine in place of 2-aminothiazole to return (22 mg, 18%) as a yellow solid.

LCMS: Purity 90-95%, [M+H]⁺ 434.2.

¹H NMR (400 MHz, DMSO-d6) δ 12.04 (br s, 1H), 9.16 (s, 1H), 8.25 (s, 1H), 8.17 (s, 1H), 7.85 (d, J=8.31 Hz, 1H), 7.75 (s, 1H), 7.69 (s, 1H), 7.39 (dd, J=1.44, 8.28 Hz, 1H), 1.78 (s, 9H).

Example 16—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(1-methylpyrazol-3-yl)-1H-indole-2-carboxamide

Prepared as described for Example 1 using 1-methyl-1H-pyrazol-3-amine in place of 2-aminothiazole to return (46 mg, 37%) as a white solid.

LCMS: Purity>95%, [M+H]⁺ 430.3.

¹H NMR (400 MHz, DMSO-d6) δ 11.80-11.89 (m, 1H), 10.95 (s, 1H), 8.26 (s, 1H), 7.80 (d, J=8.25 Hz, 1H), 7.73 (s, 1H), 7.60-7.66 (m, 1H), 7.56 (d, J=1.34 Hz, 1H), 7.36 (dd, J=1.50, 8.22 Hz, 1H), 6.63 (d, J=2.20 Hz, 1H), 3.79-3.83 (m, 3H), 1.78 (s, 9H).

Example 17—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2-methoxyethoxy)-1H-indole-2-carboxamide

Prepared as described for Example 1 using O-(2-methoxyethyl)hydroxylamine in place of 2-aminothiazole to return (31 mg, 25%) as a white solid.

LCMS: Purity 90-95%, [M+H]⁺ 424.3.

¹H NMR (400 MHz, DMSO-d6) δ 11.86 (br s, 2H), 8.24 (s, 1H), 7.78 (d, J=8.25 Hz, 1H), 7.70 (s, 1H), 7.35 (dd, J=1.47, 8.25 Hz, 1H), 7.12 (br s, 1H), 4.02-4.11 (m, 2H), 3.49-3.66 (m, J=3.70, 5.30 Hz, 2H), 3.31 (br s, 3H), 1.77 (s, 9H).

Example 18—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2-methylpyrazol-3-yl)-1H-indole-2-carboxamide

Prepared as described for Example 1 using 1-methyl-1H-pyrazol-5-amine in place of 2-aminothiazole to return (25 mg, 20%) as a beige solid.

LCMS: Purity 90-95%, [M+H]+ 430.3.

¹H NMR (400 MHz, DMSO-d6) δ 12.02 (br s, 1H), 10.42 (br s, 1H), 8.25 (s, 1H), 7.85 (d, J=8.25 Hz, 1H), 7.66-7.79 (m, 1H), 7.47 (br s, 1H), 7.43 (d, J=1.90 Hz, 1H), 7.39 (dd, J=1.47, 8.25 Hz, 1H), 6.28 (d, J=1.96 Hz, 1H), 3.74 (s, 3H), 1.75-1.80 (m, 9H).

Example 19—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-phenyl-1H-indole-2-carboxamide

Prepared as described for Example 1 using aniline in place of 2-aminothiazole to return (30 mg, 24%) as a beige solid.

LCMS: Purity>95%, [M+H]+ 426.2.

¹H NMR (400 MHz, DMSO-d6) δ 11.89-11.98 (m, 1H), 10.28 (s, 1H), 8.29 (s, 1H), 7.83-7.90 (m, 2H), 7.82 (d, J=0.92 Hz, 1H), 7.74 (s, 1H), 7.52 (d, J=1.41 Hz, 1H), 7.32-7.46 (m, 3H), 7.13 (tt, J=0.90, 7.20 Hz, 1H), 1.78 (s, 9H).

Example 20—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2-hydroxyethyl)-1H-indole-2-carboxamide

To a mixture of 6-(4-amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid (100 mg, 0.28 mmol) and PyBOP (148 mg, 0.28 mmol) in DMF (2 ml) was added triethylamine (0.12 ml, 0.84 mmol) and ethanolamine (17 μL, 0.17 mmol). The mixture was stirred at room temperature for 18 hours then diluted with water and extracted with EtOAc (3×). The combined extracts were dried over Na₂SO₄, filtered and concentrated under reduced pressure. The residue was purified by flash column chromatography (10% MeOH in DCM) to return 6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2-hydroxyethyl)-1H-indole-2-carboxamide (32 mg, 0.08 mmol, 28%) as a beige solid.

LCMS: Purity>95%, [M+H]⁺ 394.4.

¹H NMR (400 MHz, DMSO-d6) δ 11.66-11.80 (m, 1H), 8.53 (t, J=5.90 Hz, 1H), 8.24 (s, 1H), 7.77 (d, J=8.25 Hz, 1H), 7.69 (s, 1H), 7.33 (dd, J=1.47, 8.19 Hz, 1H), 7.13-7.26 (m, 1H), 4.78 (s, 1H), 3.55 (q, J=5.80 Hz, 2H), 3.37 (q, J=5.80 Hz, 2H), 1.77 (s, 9H).

Example 21—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(5-methyl-1,3,4-thiadiazol-2-yl)-1H-indole-2-carboxamide

Prepared as described for Example 1 using 5-methyl-1,3,4-thiadiazol-2-amine in place of 2-aminothiazole to return (9 mg, 7%) as a white solid.

LCMS: Purity>95%, [M+H]+ 448.3.

¹H NMR (400 MHz, DMSO-d6) δ 12.05 (br s, 1H), 8.25 (s, 1H), 8.19 (s, 1H), 7.84 (d, J=8.25 Hz, 1H), 7.74 (s, 1H), 7.68 (s, 1H), 7.39 (dd, J=1.44, 8.28 Hz, 1H), 2.64 (s, 3H), 1.78 (s, 9H).

Example 22—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(1,2,4-thiadiazol-5-yl)-1H-indole-2-carboxamide

To a suspension of 6-(4-amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid (175 mg, 0.5 mmol) in DCM (5 mL) was added oxalyl chloride (51 μL, 0.6 mmol) and a drop of DMF. The mixture was stirred at room temperature for 1 hour then concentrated under reduced pressure and azeotroped with toluene to return a yellow solid. This was redissolved in DCM (5 ml) before adding 1,2,4-thiadiazol-5-amine (56 mg, 0.5 mmol), DIPEA (0.1 ml, 0.6 mmol) and DMAP (3 mg, 5 mol %). The reaction was stirred for 24 hours at room temperature then concentrated under reduced pressure. The residue was partitioned between EtOAc and water, then filtered to remove a solid. The organic phase was separated and washed with sat. NaHCO₃ and brine, dried over Na₂SO₄, filtered and concentrated under reduced pressure. The residue was purified by flash column chromatography (0-100% EtOAc in isohexane) to return the crude product. This was further purified by preparative HPLC to return 6-(4-amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(1,2,4-thiadiazol-5-yl)-1H-indole-2-carboxamide (16 mg, 0.03 mmol, 7%) as a white solid.

LCMS: Purity 90-95%, [M+H]+ 434.2.

¹H NMR (400 MHz, DMSO-d6) δ 12.10 (br s, 1H), 8.48 (s, 1H), 8.25 (s, 1H), 8.15 (s, 1H), 7.85 (d, J=8.25 Hz, 1H), 7.75 (s, 1H), 7.67 (br s, 1H), 7.40 (dd, J=1.41, 8.31 Hz, 1H), 1.75-1.82 (m, 9H).

Example 23—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(3-thienyl)-1H-indole-2-carboxamide

Prepared as described for Example 1 using 3-aminothiophene oxalate in place of 2-aminothiazole to return (45 mg, 36%) as a white solid.

LCMS: Purity>95%, [M+H]+ 432.2.

¹H NMR (400 MHz, DMSO-d6) δ 11.90-12.01 (m, 1H), 10.80 (s, 1H), 8.25 (s, 1H), 7.84 (d, J=8.25 Hz, 1H), 7.71-7.77 (m, 2H), 7.52 (dd, J=3.21, 5.17 Hz, 1H), 7.45 (d, J=1.34 Hz, 1H), 7.34-7.41 (m, 2H), 1.78 (s, 9H).

Example 24—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-thiazol-5-yl-1H-indole-2-carboxamide

Prepared as described for Example 1 using thiazol-5-amine in place of 2-aminothiazole to return (14 mg, 11%) as a white solid.

LCMS: Purity>95%, [M+H]⁺ 433.2.

¹H NMR (400 MHz, DMSO-d6) δ 12.07 (br s, 1H), 11.74-12.01 (m, 1H), 8.65 (d, J=0.73 Hz, 1H), 8.21-8.28 (m, 1H), 7.88 (d, J=8.46 Hz, 1H), 7.83 (s, 1H), 7.75 (s, 1H), 7.50 (s, 1H), 7.40 (dd, J=1.44, 8.28 Hz, 1H), 1.73-1.83 (m, 9H).

Example 25—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-isoxazol-4-yl-1H-indole-2-carboxamide

A mixture of 6-(4-amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid (100 mg, 0.28 mmol), EDCI.HCl (109 mg, 0.57 mmol) and HOBt.H₂O (87 mg, 0.57 mmol) in DMF (4 ml) was stirred at room temperature for 1 hour before adding isoxazol-4-amine (34 mg, 0.28 mmol). After an hour, DIPEA (0.14 ml, 0.86 mmol) was added and the mixture stirred for 3 hours. Additional DIPEA (0.1 ml, 0.6 mmol) was added and the reaction stirred at room temperature for 18 hours then concentrated under reduced pressure. The residue was partitioned between DCM and water, separated and the organic phase dried over Na₂SO₄, filtered and concentrated under reduced pressure, The residue was purified by flash column chromatography (0-5% MeOH in DCM) to return the crude product. This was further purified by preparative HPLC to return 6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-isoxazol-4-yl-1H-indole-2-carboxamide (7 mg, 0.02 mmol, 6%) as a white solid.

LCMS: Purity>95%, [M+H]⁺ 417.2.

¹H NMR (400 MHz, DMSO-d6) δ 12.01 (s, 1H), 10.88 (s, 1H), 9.28 (s, 1H), 8.78 (s, 1H), 8.25 (s, 1H), 7.86 (d, J=8.31 Hz, 1H), 7.75 (s, 1H), 7.40 (d, J=1.47 Hz, 1H), 7.38-7.39 (m, 1H), 1.78 (s, 9H)

Example 26—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(4-methylthiazol-2-yl)-1H-indole-2-carboxamide

Prepared as described for Example 1 using 4-methylthiazol-2-amine in place of 2-aminothiazole to return (5 mg, 1%) as a beige solid.

LCMS: Purity>95%, [M+H]⁺ 447.2.

¹H NMR (400 MHz, DMSO-d6) δ 12.70 (br s, 1H), 12.02 (br s, 1H), 8.25 (s, 1H), 7.83 (d, J=8.01 Hz, 1H), 7.74 (s, 1H), 7.69 (s, 1H), 7.39 (dd, J=1.44, 8.28 Hz, 1H), 6.82 (s, 1H), 2.33 (d, J=0.92 Hz, 3H), 1.78 (s, 9H).

Example 27—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(1-ethylpyrazol-3-yl)-1H-indole-2-carboxamide

Prepared as described for Example 1 using 1-ethyl-1H-pyrazol-3-amine in place of 2-aminothiazole to return (26 mg, 20%) as an off-white solid.

LCMS: Purity>95%, [M+H]⁺ 444.3.

¹H NMR (400 MHz, DMSO-d6) δ 11.77-11.90 (m, 1H), 10.98 (s, 1H), 8.25 (s, 1H), 7.79 (d, J=8.31 Hz, 1H), 7.72 (s, 1H), 7.68 (s, 1H), 7.57 (d, J=1.28 Hz, 1H), 7.36 (dd, J=1.50, 8.22 Hz, 1H), 6.63 (d, J=2.26 Hz, 1H), 4.10 (q, J=7.25 Hz, 2H), 1.77 (s, 9H), 1.40 (t, J=7.24 Hz, 3H).

Example 28—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-[1-(2-methoxyethyl)pyrazol-3-yl]-1H-indole-2-carboxamide

Prepared as described for Example 1 using 1-(2-methoxyethyl)-1H-pyrazol-3-amine in place of 2-aminothiazole to return (29 mg, 21%) as a white solid.

LCMS: Purity>95%, [M+H]⁺ 474.3.

¹H NMR (400 MHz, DMSO-d6) δ 11.81-11.88 (m, 1H), 10.99 (s, 1H), 8.22-8.26 (m, 1H), 7.79 (d, J=8.25 Hz, 1H), 7.72 (s, 1H), 7.66 (d, J=2.26 Hz, 1H), 7.57 (d, J=1.28 Hz, 1H), 7.36 (dd, J=1.47, 8.25 Hz, 1H), 6.64 (d, J=2.26 Hz, 1H), 4.22 (t, J=5.32 Hz, 2H), 3.70 (t, J=5.32 Hz, 2H), 3.25 (s, 3H), 1.77 (s, 9H).

Example 29—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-[1-(2-fluoroethyl)pyrazol-3-yl]-1H-indole-2-carboxamide

Prepared as described for Example 1 using 1-(2-fluoroethyl)-1H-pyrazol-3-amine in place of 2-aminothiazole to return (32 mg, 24%) as a white solid.

LCMS: Purity>95%, [M+H]+ 462.3.

¹H NMR (400 MHz, DMSO-d6) δ 11.81-11.90 (m, 1H), 11.03 (s, 1H), 8.24 (s, 1H), 7.80 (d, J=8.25 Hz, 1H), 7.72 (d, J=2.02 Hz, 2H), 7.58 (d, J=1.41 Hz, 1H), 7.36 (dd, J=1.50, 8.28 Hz, 1H), 6.68 (d, J=2.26 Hz, 1H), 4.84 (t, J=4.71 Hz, 1H), 4.72 (t, J=4.71 Hz, 1H), 4.43 (t, J=4.71 Hz, 1H), 4.36 (t, J=4.71 Hz, 1H), 1.77 (s, 9H).

Example 30—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(3-pyridyl)-1H-indole-2-carboxamide

Prepared as described for Example 1 using 3-aminopyridine in place of 2-aminothiazole to return (25 mg, 100%) as a yellow solid.

LCMS: purity>95%, [M−H]⁻ 427.3.

¹H NMR (400 MHz, DMSO-d6) δ 11.93-12.04 (m, 1H), 10.50 (s, 1H), 8.99 (d, J=2.20 Hz, 1H), 8.34 (dd, J=1.44, 4.68 Hz, 1H), 8.21-8.27 (m, 2H), 7.87 (d, J=8.25 Hz, 1H), 7.75 (s, 1H), 7.54 (d, J=1.41 Hz, 1H), 7.37-7.47 (m, 2H), 1.78 (s, 9H).

Example 31—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(4-pyridyl)-1H-indole-2-carboxamide

Prepared as described for Example 1 using 4-aminopyridine in place of 2-aminothiazole to return (22 mg, 9%) as a yellow solid.

LCMS: purity>95%, [M−H]⁻ 427.3.

¹H NMR (400 MHz, DMSO-d6) δ 11.98-12.05 (m, 1H), 10.60 (s, 1H), 8.48-8.53 (m, 2H), 8.25 (s, 1H), 7.88 (d, J=8.31 Hz, 1H), 7.81-7.85 (m, 2H), 7.75 (s, 1H), 7.58 (d, J=1.34 Hz, 1H), 7.40 (dd, J=1.44, 8.28 Hz, 1H), 1.78 (s, 9H).

Example 32—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-[1-(2-hydroxyethyl)pyrazol-3-yl]-1H-indole-2-carboxamide

Prepared as described for Example 1 using 2-(3-amino-1H-pyrazol-1-yl)ethan-1-ol in place of 2-aminothiazole to return (15 mg, 7%) as a beige solid.

LCMS: purity>95%, [M−H]⁻ 460.3.

¹H NMR (400 MHz, DMSO-d6) δ 11.81-11.88 (m, 1H), 10.99 (s, 1H), 8.26 (s, 1H), 7.80 (d, J=8.25 Hz, 1H), 7.72 (s, 1H), 7.65 (d, J=2.20 Hz, 1H), 7.57 (d, J=1.41 Hz, 1H), 7.36 (dd, J=1.47, 8.25 Hz, 1H), 6.64 (d, J=2.26 Hz, 1H), 4.10 (t, J=5.65 Hz, 2H), 3.75 (t, J=5.59 Hz, 2H), 1.78 (s, 9H).

Example 33—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-3-chloro-N-methyl-1H-indole-2-carboxamide

Prepared as described for Example 1 using 6-(4-amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-3-chloro-1H-indole-2-carboxylic acid and methylamine hydrochloride in place of 6-(4-amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid and 2-aminothiazole to return (14 mg, 14%) as a white solid.

LCMS: purity>95%, [M−H]− 396.2.

¹H NMR (300 MHz, DMSO-d6) δ 12.07 (br s, 1H), 8.25 (s, 1H), 7.97 (q, J=4.43 Hz, 1H), 7.70-7.78 (m, 2H), 7.47 (d, J=8.18 Hz, 1H), 2.90 (d, J=4.62 Hz, 3H), 1.75-1.90 (m, 9H).

Example 34—6-(4-Amino-1-isopropyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-cyclopropyl-1H-indole-2-carboxamide

Prepared as described for Example 1 using 6-(4-amino-1-isopropyl-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid and cyclopropylmethanamine in place of 6-(4-amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid and 2-aminothiazole to return (20 mg, 9%) as a white solid.

LCMS: purity>95%, [M+H]⁺ 376.3.

¹H NMR (400 MHz, DMSO-d6) δ 8.25 (s, 1H), 7.80 (d, J=8.25 Hz, 1H), 7.74 (s, 1H), 7.36 (dd, J=1.53, 8.25 Hz, 1H), 7.19 (s, 1H), 5.08 (spt, J=6.63 Hz, 1H), 2.82-2.91 (m, 1H), 1.51 (d, J=6.72 Hz, 6H), 0.70-0.83 (m, 2H), 0.59-0.68 (m, 2H).

Example 35—6-(4-Amino-1-isopropyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2-fluoroethyl)-1H-indole-2-carboxamide

Prepared as described for Example 1 using 6-(4-amino-1-isopropyl-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid and 2-fluoroethylamine hydrochloride in place of 6-(4-amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid and 2-aminothiazole to return (172 mg, 51%) as a tan solid.

LCMS: purity>95%, [M+H]⁺ 382.2.

¹H NMR (400 MHz, DMSO-d6) δ 11.72-11.83 (m, 1H), 8.79 (t, J=5.62 Hz, 1H), 8.24 (s, 1H), 7.79 (d, J=8.31 Hz, 1H), 7.73 (s, 1H), 7.36 (dd, J=1.53, 8.25 Hz, 1H), 7.24 (dd, J=0.67, 2.02 Hz, 1H), 5.08 (spt, J=6.70 Hz, 1H), 4.64 (t, J=5.07 Hz, 1H), 4.52 (t, J=5.04 Hz, 1H), 3.62 (qd, J=5.32, 26.78 Hz, 2H), 1.51 (d, J=6.72 Hz, 6H).

Example 36—6-(4-Amino-1-isopropyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-ethoxy-1H-indole-2-carboxamide

Prepared as described for Example 1 using 6-(4-amino-1-isopropyl-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid and O-ethylhydroxylamine in place of 6-(4-amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid and 2-aminothiazole to return (68 mg, 60%) as a beige solid.

LCMS: purity>95%, [M+H]+ 380.2.

¹H NMR (400 MHz, DMSO-d6) δ 11.85 (s, 1H), 11.74 (br s, 1H), 8.25 (s, 1H), 7.79 (d, J=8.31 Hz, 1H), 7.72 (s, 1H), 7.37 (dd, J=1.47, 8.25 Hz, 1H), 7.10 (s, 1H), 5.08 (spt, J=6.71 Hz, 1H), 3.98 (q, J=6.97 Hz, 2H), 1.51 (d, J=6.66 Hz, 6H), 1.23-1.27 (m, 3H).

Example 37—6-(4-Amino-1-isopropyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-thiazol-2-yl-1H-indole-2-carboxamide

Prepared as described for Example 1 using 6-(4-amino-1-isopropyl-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid in place of 6-(4-amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid to return (42 mg, 10%) as a yellow solid.

LCMS: purity>95%, [M+H]+ 419.2.

¹H NMR (400 MHz, DMSO-d6) δ 12.76 (br s, 1H), 12.06 (br s, 1H), 8.25 (s, 1H), 7.85 (d, J=8.31 Hz, 1H), 7.77 (s, 1H), 7.75 (br s, 1H), 7.58 (d, J=3.55 Hz, 1H), 7.42 (dd, J=1.47, 8.25 Hz, 1H), 7.30 (d, J=3.48 Hz, 1H), 5.09 (spt, J=6.70 Hz, 1H), 1.52 (d, J=6.66 Hz, 6H).

Example 38—6-(4-Amino-1-isopropyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(1-methylpyrazol-3-yl)-1H-indole-2-carboxamide

Prepared as described for Example 1 using 6-(4-amino-1-isopropyl-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid and 1-methyl-1H-pyrazol-3-amine in place of 6-(4-amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid and 2-aminothiazole to return (49 mg, 26%) as a white solid.

LCMS: purity>95%, [M+H]⁺ 416.2.

¹H NMR (400 MHz, DMSO-d6) δ 11.81-11.88 (m, 1H), 10.96 (s, 1H), 8.25 (s, 1H), 7.80 (d, J=7.94 Hz, 1H), 7.74 (s, 1H), 7.63 (d, J=2.14 Hz, 1H), 7.56 (d, J=1.34 Hz, 1H), 7.38 (dd, J=1.50, 8.28 Hz, 1H), 6.63 (d, J=2.20 Hz, 1H), 5.08 (spt, J=6.70 Hz, 1H), 3.81 (s, 3H), 1.51 (d, J=6.66 Hz, 6H).

Example 39—6-(4-Amino-1-isopropyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(1,3,4-thiadiazol-2-yl)-1H-indole-2-carboxamide

Prepared as described for Example 1 using 6-(4-amino-1-isopropyl-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid and 1,3,4-thiadiazol-2-amine in place of 6-(4-amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxylic acid and 2-aminothiazole to return (3 mg, 2%) as a tan solid.

LCMS: purity>95%, [M+H]+ 420.1.

¹H NMR (400 MHz, DMSO-d6) δ 11.94 (br s, 1H), 9.08 (br s, 1H), 8.25 (s, 1H), 8.21 (s, 1H), 7.83 (d, J=8.31 Hz, 1H), 7.77 (s, 1H), 7.58 (br s, 1H), 7.39 (br d, J=8.25 Hz, 1H), 5.08 (quin, J=6.71 Hz, 1H), 1.52 (d, J=6.72 Hz, 6H).

Example 40—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-methyl-1H-indole-2-carboxamide

A mixture of 6-bromo-N-methyl-1H-indole-2-carboxamide (253 mg, 1 mmol), XPhos-Pd-G2 (16 mg, 0.02 mmol), XPhos (19 mg, 0.04 mmol), B₂(OH)₄ (269 mg, 3 mmol) and KOAc (294 mg, 3 mmol) in EtOH (10 ml) was degassed with argon for 5 mins then heated at 80° C. for 2 hours. A degassed aqueous solution of K₂CO₃ (1.8M, 1.7 ml, 3.0 mmol) and a degassed solution of 3-bromo-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine (270 mg, 1.0 mmol) in THF (2 ml) was added and the mixture heated at 80° C. for 18 hours. The reaction was cooled to room temperature, diluted with water and extracted with EtOAc (3×). The combined organic phases were dried over Na₂SO₄, filtered and concentrated under reduced pressure to return a residue which was purified by flash column chromatography to return 204 mg of a solid which was further purified by preparative HPLC to return 6-(4-amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-methyl-1H-indole-2-carboxamide (76 mg, 21%) as a white solid.

LCMS: purity>95%, [M−H]⁻ 362.2.

¹H NMR (400 MHz, DMSO-d6) δ 11.74 (s, 1H), 8.52 (q, J=4.42 Hz, 1H), 8.24 (s, 1H), 7.77 (d, J=8.25 Hz, 1H), 7.70 (s, 1H), 7.33 (dd, J=1.50, 8.22 Hz, 1H), 7.14 (d, J=1.28 Hz, 1H), 2.84 (d, J=4.65 Hz, 3H), 1.77 (s, 9H).

Example 41—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-cyclopropyl-1H-indole-2-carboxamide

Prepared as described for Example 40 using 6-bromo-N-cyclopropyl-1H-indole-2-carboxamide in place of 6-bromo-N-methyl-1H-indole-2-carboxamide to return (78 mg, 31%) as a white solid.

LCMS: purity>95%, [M−H]⁻ 390.2.

¹H NMR (400 MHz, DMSO-d6) δ 11.71 (s, 1H), 8.52 (d, J=4.10 Hz, 1H), 8.24 (s, 1H), 7.76 (d, J=8.25 Hz, 1H), 7.69 (s, 1H), 7.33 (dd, J=1.47, 8.25 Hz, 1H), 7.17 (d, J=1.28 Hz, 1H), 2.87 (qq, J=3.90, 7.30 Hz, 1H), 1.77 (s, 9H), 0.67-0.77 (m, 2H), 0.57-0.67 (m, 2H).

Example 42—6-(4-Amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-N-ethyl-1H-indole-2-carboxamide

Prepared as described for Example 40 using 6-bromo-N-ethyl-1H-indole-2-carboxamide in place of 6-bromo-N-methyl-1H-indole-2-carboxamide to return (77 mg, 31%) as a white solid.

LCMS: purity>95%, [M−H]− 378.2.

¹H NMR (400 MHz, DMSO-d6) δ 11.66-11.77 (m, 1H), 8.54 (t, J=5.59 Hz, 1H), 8.20-8.26 (m, 1H), 7.77 (d, J=8.25 Hz, 1H), 7.69 (s, 1H), 7.33 (dd, J=1.50, 8.22 Hz, 1H), 7.17 (d, J=1.28 Hz, 1H), 3.33-3.38 (m, 2H), 1.77 (s, 9H), 1.16 (t, J=7.21 Hz, 3H).

Example 43—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-cyclobutyl-1H-indole-2-carboxamide

Prepared as described for Example 40 using 6-bromo-N-cyclobutyl-1H-indole-2-carboxamide in place of 6-bromo-N-methyl-1H-indole-2-carboxamide to return (93 mg, 30%) as a white solid.

LCMS: purity 85-90%, [M−H]⁻ 404.3.

¹H NMR (400 MHz, DMSO-d6) δ 11.71 (br s, 1H), 8.69 (d, J=7.76 Hz, 1H), 8.24 (s, 1H), 7.78 (d, J=8.25 Hz, 1H), 7.69 (s, 1H), 7.34 (dd, J=1.50, 8.22 Hz, 1H), 7.24 (d, J=1.00 Hz, 1H), 4.47 (br d, J=8.31 Hz, 1H), 2.21-2.32 (m, 2H), 2.03-2.16 (m, 2H), 1.77 (s, 9H), 1.67-1.75 (m, 2H).

Example 44—6-(4-Amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxamide

Prepared as described for Example 40 using 6-bromo-N-methoxy-1H-indole-2-carboxamide in place of 6-bromo-N-methyl-1H-indole-2-carboxamide to return not the expected 6-(4-amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-N-methoxy-1H-indole-2-carboxamide but 6-(4-amino-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-3-yl)-1H-indole-2-carboxamide (17 mg, 5%) as a white solid.

LCMS: purity>95%, [M−H]⁻ 350.2.

¹H NMR (400 MHz, DMSO-d6) δ 11.66-11.75 (m, 1H), 8.24 (s, 1H), 8.02 (br s, 1H), 7.77 (d, J=8.25 Hz, 1H), 7.69 (s, 1H), 7.42 (br s, 1H), 7.33 (dd, J=1.50, 8.22 Hz, 1H), 7.20 (d, J=1.34 Hz, 1H), 1.77 (s, 9H).

Example 45—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-3-fluoro-N-methyl-1H-indole-2-carboxamide

Prepared as described for Example 40 using 6-bromo-3-fluoro-N-methyl-1H-indole-2-carboxamide in place of 6-bromo-N-methyl-1H-indole-2-carboxamide to return (12 mg, 17%) as a white solid.

LCMS: purity>95%, [M+H]+ 382.2.

¹H NMR (400 MHz, DMSO-d6) δ 11.62 (s, 1H), 8.24 (s, 1H), 7.85-7.97 (m, 1H), 7.77 (d, J=8.38 Hz, 1H), 7.65 (s, 1H), 7.40 (dd, J=1.34, 8.38 Hz, 1H), 2.86 (d, J=4.58 Hz, 3H), 1.77 (s, 9H).

Example 46—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N,3-dimethyl-1H-indole-2-carboxamide

Prepared as described for Example 40 using 6-bromo-N,3-dimethyl-1H-indole-2-carboxamide in place of 6-bromo-N-methyl-1H-indole-2-carboxamide to return (28 mg, 20%) as a white solid.

LCMS: purity>95%, [M+H]+ 378.2.

¹H NMR (400 MHz, DMSO-d6) δ 11.38 (s, 1H), 8.24 (s, 1H), 7.89 (q, J=4.30 Hz, 1H), 7.75 (d, J=8.19 Hz, 1H), 7.63 (s, 1H), 7.33 (dd, J=1.47, 8.25 Hz, 1H), 2.84 (d, J=4.58 Hz, 3H), 2.52-2.55 (m, 3H), 1.77 (s, 9H).

Example 47—6-(4-Amino-1-tert-butyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-(2,5-dimethylpyrazol-3-yl)-1H-indole-2-carboxamide

Prepared as described for Example 40 using 6-bromo-N-(1,3-dimethyl-1H-pyrazol-5-yl)-1H-indole-2-carboxamide in place of 6-bromo-N-methyl-1H-indole-2-carboxamide to return (27 mg, 5%) as a white solid.

LCMS: purity>95%, [M−H]⁻ 444.3.

¹H NMR (400 MHz, DMSO-d6) δ 12.01 (br s, 1H), 10.25-10.45 (m, 1H), 8.25 (s, 1H), 7.85 (d, J=8.18 Hz, 1H), 7.73 (s, 1H), 7.46 (s, 1H), 7.39 (dd, J=1.43, 8.27 Hz, 1H), 6.06 (s, 1H), 3.65 (s, 3H), 2.15 (s, 3H), 1.77 (s, 9H).

Example 48—6-(4-Amino-1-isopropyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-methyl-1H-indole-2-carboxamide

Prepared as described for Example 40 using 3-bromo-1-isopropyl-1H-pyrazolo[3,4-d]pyrimidin-4-amine in place of 3-bromo-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine to return (81 mg, 39%) as a white solid.

LCMS: purity>95%, [M+H]⁺ 350.3.

¹H NMR (400 MHz, DMSO-d6) δ 11.68-11.81 (m, 1H), 8.53 (q, J=4.44 Hz, 1H), 8.24 (s, 1H), 7.77 (s, 1H), 7.72 (s, 1H), 7.35 (dd, J=1.50, 8.22 Hz, 1H), 7.15 (d, J=1.28 Hz, 1H), 5.08 (spt, J=6.69 Hz, 1H), 2.84 (d, J=4.65 Hz, 3H), 1.51 (d, J=6.66 Hz, 6H).

Example 49—6-(4-Amino-1-ethyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-methyl-1H-indole-2-carboxamide

Prepared as described for Example 40 using 3-bromo-1-ethyl-1H-pyrazolo[3,4-d]pyrimidin-4-amine in place of 3-bromo-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine to return (23 mg, 17%) as a white solid.

LCMS: purity>95%, [M+H]+ 336.2.

¹H NMR (400 MHz, DMSO-d6) δ 11.72-11.82 (m, 1H), 8.53 (q, J=4.44 Hz, 1H), 8.25 (s, 1H), 7.78 (d, J=8.43 Hz, 1H), 7.72 (s, 1H), 7.35 (dd, J=1.50, 8.22 Hz, 1H), 7.14 (d, J=1.34 Hz, 1H), 4.39 (q, J=7.21 Hz, 2H), 2.84 (d, J=4.58 Hz, 3H), 1.43 (t, J=7.21 Hz, 3H).

Example 50—6-(4-Amino-1-cyclopropyl-pyrazolo[3,4-d]pyrimidin-3-yl)-N-methyl-1H-indole-2-carboxamide

Prepared as described for Example 40 using 3-bromo-1-cyclopropyl-1H-pyrazolo[3,4-d]pyrimidin-4-amine in place of 3-bromo-1-(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine to return (36 mg, 23%) as a white solid.

LCMS: purity>95%, [M+H]+ 348.3.

¹H NMR (400 MHz, DMSO-d6) δ 11.71-11.81 (m, 1H), 8.53 (q, J=4.52 Hz, 1H), 8.26 (s, 1H), 7.77 (d, J=8.25 Hz, 1H), 7.69 (s, 1H), 7.32 (dd, J=1.53, 8.25 Hz, 1H), 7.14 (d, J=1.34 Hz, 1H), 3.87 (tt, J=3.77, 7.35 Hz, 1H), 2.83 (d, J=4.58 Hz, 3H), 1.16-1.27 (m, 2H), 1.03-1.16 (m, 2H).

The following compounds were prepared in an analogous manner to those described above, using a synthetic procedure similar to that detailed for Example 40:

Example Structure Name 51

6-(4-amino-1-tert-butyl- pyrazolo[3,4-d]pyrimidin- 3-yl)-N-isopropyl-1H- indole-2-carboxamide 52

6-[4-amino-1-(3-hydroxy- 3-methyl- cyclopentyl)pyrazolo[3,4- d]pyrimidin-3-yl]-N- methyl-1H-indole-2- carboxamide 53

6-(4-amino-1-isopropyl- pyrazolo[3,4-d]pyrimidin- 3-yl)-N,3-dimethyl-1H- indole-2-carboxamide 54

6-[4-amino-1-(3- methoxpropyl)pyrazolo [3,4-d]pyrimidin-3-yl]-N- methyl-1H-indole-2- carboxamide 55

6-(4-amino-1-cyclobutyl- pyrazolo[3,4-d]pyrimidin- 3-yl)-N-methyl-1H-indole- 2-carboxamide 56

tert-butyl 3-[4-amino-3- [2-(methylcarbamoyl)- 1H-indol-6- yl]pyrazolo[3,4- d]pyrimidin-1- yl]azetidine-1- carboxylate

Example 60—Biological Data RET and KDR Enzyme Assays

Kinase activity was detected using CisBio HTRF kinEASE kit based on time-resolved fluorescence transfer (FRET). The assay was performed in 384-well white plates (Corning #3574) in a reaction volume of 10 μL containing 1× CisBio enzymatic buffer supplemented with a final concentration of 5 mM MgCl₂, 1 mM DTT, 10 nM SEB and 0.01% Triton X100 for RET. The same buffer was used for the KDR biochemical assay with the addition of 2 mM MnCl₂.

Inhibitors were pre-incubated in the plate for 15 mins with 5 μL kinase and assay buffer at the following concentrations; 13 pM RET (Carna Biosciences; 08-159) and 150 pM KDR (Millipore; 14-630). The reaction was initiated by the addition of 5 μL ATP and substrate at 2× final reaction concentrations. For RET, this was 18 μM and 2 μM; for KDR, this was 16 μM and 1 μM, respectively. Reactions were performed at ATP K_(m) for each target. The assay was allowed to proceed at room temperature for 20 mins before terminating with the addition of 10 μL HTRF detection buffer containing EDTA supplemented with TK-antibody labelled with Eu³⁺-Cryptate (1:100 dilution) and streptavidin-XL665 (128 nM). Following incubation at room temperature for 1 hour, FRET signal was measured using the Pherastar FS Microplate Reader.

Activity data (IC50) for the compounds of the present invention against RET and KDR enzymes is shown in Table 1 below.

TABLE 1 RET and KDR enzyme activity data RET Enzyme IC50 KDR Enzyme IC50 Example (μM) (μM) Selectivity 1 23.9 2 0.569 54.7 96.1 3 0.189 41.5 219 4 0.226 9.15 40.6 5 0.0117 4.67 399 6 0.065 13.2 203 7 2.4 30 12.5 8 0.933 30 32.2 9 2.94 30 10.2 10 0.223 31.5 141 11 1.36 150 111 12 0.0903 22.9 254 13 0.00947 8.25 871 14 0.0691 30 434 15 0.0198 4.1 207 16 0.0176 30 1700 17 0.0248 30 1210 18 0.0936 30 320 19 1.89 30 15.9 20 0.0237 3 127 21 0.0509 30 590 22 0.131 8.24 62.8 23 2.29 30 13.1 24 0.0813 21 259 25 0.444 26.1 58.8 26 30 27 0.119 30 252 28 0.141 30 213 29 0.0998 30 301 30 0.206 30 146 31 0.211 30 142 32 0.0939 30 319 33 0.0241 3.41 141 34 0.0291 11.2 383 35 0.039 11.5 295 36 0.0204 4.68 229 37 0.00707 38 0.0342 11.6 339 39 0.000709 0.69 973 40 0.051 7.87 154 41 0.0563 15.1 268 42 0.0552 16.1 291 43 0.302 9.3 30.9 44 0.0441 7.09 161 45 0.189 16.2 85.7 46 0.0422 0.733 17.4 47 0.416 30 72.1 48 0.0499 6.57 132 49 0.156 7.83 50.1 50 23.9 51 3.63 30 8.26 52 0.0744 13 175 53 0.0121 0.456 37.8 54 0.374 29.3 78.1 55 0.0552 7.59 138 56 0.363 25.2 69.3

BaF3 Cell Assay

The system originally developed by Daley and Baltimore¹⁶ was used, whereby IL3-dependent BaF3 cells are modified to express an activated recombinant kinase. Following removal of IL3, the modified cells are dependent on the activity of the recombinant kinase for survival and proliferation. The BaF3 cell lines, expressing KIF51B-RET (gift from Pasi Janne⁷) and KDR (Advanced Cellular Dynamics, San Diego) were maintained in RPMI-1640 media containing 10% FIBS and appropriate antibiotics. Non-modified BaF3 cells (WT) were maintained in RPMI-1640 media containing 10% FIBS and supplemented with 10 ng/mL recombinant mouse IL3 (R&D systems). For assessment of compound I050, cells were plated into 384-well plates at 1500 or 3000 cells per well in 30 μL culture medium and compounds dispensed using an acoustic liquid handling platform (LABCYTE). Following incubation of the cells for 48 hours at 37° C. in a humidified 5% CO₂ atmosphere, viability was determined by addition of 10 μL CellTiter-Glo reagent (Promega) and measurement of luminescence.

Cell activity data is presented in Table 2 below.

TABLE 2 Cell activity data RET Cell KDR Cell Example IC50 (μM) IC50 (μM) Selectivity 1 0.0836 0.919 11 2 0.311 7.59 24.4 3 0.455 10 22 4 0.118 5.59 47.4 5 0.0463 4.76 103 6 0.0891 3.25 36.5 7 0.559 10 17.9 8 0.429 10 23.3 9 0.65 6.49 9.99 10 0.203 4.12 20.3 11 0.41 4.26 10.4 12 0.167 4.73 28.3 13 0.0746 5.11 68.4 14 0.369 7.85 21.3 15 0.0164 1.98 121 16 0.067 10 149 17 0.561 10 17.8 18 0.589 10 17 19 0.811 9.36 11.5 20 0.667 10 15 21 0.356 10 28.1 22 0.303 10 33 23 0.134 6.85 51.1 24 0.0416 9.34 225 25 0.284 4.73 16.6 26 0.912 10 11 27 0.0528 10 189 28 0.079 10 127 29 0.0597 10 168 30 0.373 10 26.8 31 0.275 10 36.4 32 0.194 10 51.5 33 0.0377 1.84 48.7 34 0.108 5.73 52.9 35 0.126 4.93 39.2 36 0.119 8.56 71.9 37 0.00947 0.702 74.1 38 0.0664 10 151 39 0.0213 2.66 125 40 0.101 1.51 15 41 0.176 6.28 35.7 42 0.183 6.07 33.1 43 0.134 5.82 43.4 44 0.211 3.41 16.2 45 0.0773 6.57 85.1 46 0.0314 0.704 22.4 47 0.589 10 17 48 0.124 1.56 12.6 49 0.287 3 10.5 50 0.222 3.85 17.3

While specific embodiments of the invention have been described herein for the purpose of reference and illustration, various modifications will be apparent to a person skilled in the art without departing from the scope of the invention as defined by the appended claims.

REFERENCES

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1-22. (canceled)
 23. A compound of formula Id:

or a pharmaceutically acceptable salt thereof, wherein: R₁ is a group of the formula: -L-Y-Q L is absent; Y is absent; and Q is (1-6C)alkyl or (3-1° C.)cycloalkyl; wherein Q is optionally substituted by one or more substituent groups independently selected from (1-4C)alkyl and OR_(c), wherein each R_(c) is hydrogen; X₄ is CR_(n); R_(n) is hydrogen or halo; R₂ is hydrogen; and Q₃ is hydrogen, (1-6C)alkyl, (1-6C)alkoxy, (3-8C)cycloalkyl, or heteroaryl; wherein Q₃ is optionally substituted by one or more substituent groups independently selected from (1-4C)alkyl, halo, (1-4C)haloalkyl, and OR_(t), wherein each R_(t) is hydrogen; or Q3 is optionally substituted by a group of the formula: -L₄-L_(Q4)-Z₄ L₄ is absent or is (1-3C)alkylene; L_(Q4) is absent or is O; and Z₄ is hydrogen, (1-6C)alkyl, or (3-8C)cycloalkyl.
 24. The compound of claim 23, or a pharmaceutically acceptable salt thereof, wherein: R₁ is (1-6C)alkyl or (3-6C)cycloalkyl optionally substituted by one or more groups independently selected from (1-4C)alkyl and OR_(c), wherein R_(c) is hydrogen.
 25. The compound of claim 24, or a pharmaceutically acceptable salt thereof, wherein: R₁ is (1-6C)alkyl.
 26. The compound of claim 25, or a pharmaceutically acceptable salt thereof, wherein: R₁ is tert-butyl.
 27. The compound of claim 23, or a pharmaceutically acceptable salt thereof, wherein: X₄ is CR_(n); and R_(n) is hydrogen.
 28. The compound of claim 23, or a pharmaceutically acceptable salt thereof, wherein: Q₃ is hydrogen, (1-6C)alkyl, (1-6C)alkoxy, (3-8C)cycloalkyl, or heteroaryl; wherein Q₃ is optionally substituted by one or more substituent groups independently selected from (1-4C)alkyl, halo, (1-4C)haloalkyl, and OR_(t), wherein each R_(t) is hydrogen; or Q₃ is optionally substituted by a group of the formula: -L₄-L_(Q4)-Z₄ L₄ is absent or is (1-2C)alkylene; L_(Q4) is absent or is O; and Z₄ is hydrogen, (1-6C)alkyl, or (3-8C)cycloalkyl.
 29. A compound, or a pharmaceutically acceptable salt thereof, which is:


30. A pharmaceutical formulation comprising the compound of claim 23, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier or excipient.
 31. A method of treating a cancer in which RET kinase activity is implicated in a subject in need thereof, said method comprising administering a therapeutically effective amount of the compound of claim 23, or a pharmaceutically acceptable salt thereof, to the subject.
 32. The method of claim 31, wherein the cancer is leukemia, lung cancer, colon cancer, breast cancer, ovarian cancer, prostate cancer, liver cancer, pancreatic cancer, brain cancer, skin cancer, medullary thyroid cancer, or non-small cell lung cancer.
 33. The method according of claim 31, wherein the cancer is a malignant neoplasm, a malignant tumor, or a solid tumor.
 34. The method of claim 31, wherein the cancer comprises a RET mutation.
 35. The method of claim 34, wherein the RET mutation is a RET fusion translocation.
 36. The method of claim 35, wherein the RET fusion translocation is KIF5B-RET or CCDC6-RET. 